MFG-Q1
 
Quarterly Report
May 31, 2026
MFS®  Government 
Securities Fund  
 
Portfolio of Investments
5/31/26 (unaudited)
The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.
 
Issuer
 
 
Shares/Par
Value ($)
Bonds – 102.9%
Asset-Backed & Securitized – 8.0%
3650R Commercial Mortgage Trust, 2021-PF1, “XA”, 0.988%, 11/15/2054 (i)
 
$
21,350,058
$680,896
ACREC 2021-FL1 Ltd., “AS”, FLR, 5.24% ((SOFR - 1mo. + 0.11448%) + 1.5%), 10/16/2036 (n)
 
 
1,977,559
1,977,345
Affirm, Inc., 2026-X1, “A”, 4.27%, 4/15/2031 (n)
 
 
2,908,000
2,908,699
AmeriCredit Automobile Receivables Trust, 2026-1, “A”, 4.16%, 7/12/2029 (n)
 
 
7,014,738
7,014,393
AREIT 2022-CRE6 Trust, “AS”, FLR, 5.288% (SOFR - 30 day + 1.65%), 1/20/2037 (n)
 
 
7,155,500
7,142,155
ARI Fleet Lease Trust, 2023-B, “A2”, 6.05%, 7/15/2032 (n)
 
 
285,699
286,899
Babson CLO Ltd., 2021-3A, “B1R”, FLR, 5.305% (SOFR - 3mo. + 1.63%), 1/18/2035 (n)
 
 
5,500,000
5,501,380
BBCMS Mortgage Trust, 2021-C10, “XA”, 1.191%, 7/15/2054 (i)
 
 
18,917,853
846,120
BBCMS Mortgage Trust, 2021-C9, “XA”, 1.54%, 2/15/2054 (i)
 
 
13,026,809
738,117
BBCMS Mortgage Trust, 2022-C18, “XA”, 0.48%, 12/15/2055 (i)
 
 
22,324,300
700,548
BDS 2024-FL13 Ltd., “A”, FLR, 5.189% (SOFR - 1mo. + 1.5762%), 9/19/2039 (n)
 
 
1,476,347
1,477,101
Benchmark 2021-B23 Mortgage Trust, “XA”, 1.254%, 2/15/2054 (i)
 
 
42,396,459
1,779,524
Benchmark 2021-B24 Mortgage Trust, “XA”, 1.078%, 3/15/2054 (i)
 
 
24,537,983
882,324
Benchmark 2021-B26 Mortgage Trust, “XA”, 0.843%, 6/15/2054 (i)
 
 
35,818,352
1,061,423
Benchmark 2021-B27 Mortgage Trust, “XA”, 1.231%, 7/15/2054 (i)
 
 
32,534,167
1,387,602
Benchmark 2021-B28 Mortgage Trust, “XA”, 1.216%, 8/15/2054 (i)
 
 
38,091,062
1,721,964
Benchmark 2021-B29 Mortgage Trust, “XA”, 0.988%, 9/15/2054 (i)
 
 
43,532,577
1,386,430
Business Jet Securities LLC, 2024-1A, “A”, 6.197%, 5/15/2039 (n)
 
 
857,634
867,020
BX Trust, 2026-CLS, “A”, 5.027%, 5/15/2043 (n)
 
 
3,995,000
4,003,735
BXMT 2021-FL4 Ltd., “AS”, FLR, 5.291% ((SOFR - 1mo. + 0.11448%) + 1.3%), 5/15/2038 (n)
 
 
7,779,500
7,769,327
Chesapeake Funding II LLC, 2023-2A, “A2”, FLR, 4.743% (SOFR - 30 day + 1.1%), 10/15/2035 (n)
 
 
865,177
865,654
Citigroup Commercial Mortgage Trust, 2019-XA, “C7”, 0.814%, 12/15/2072 (i)(n)
 
 
20,707,780
526,932
Commercial Mortgage Pass-Through Certificates, 2021-BN31, “XA”, 1.279%, 2/15/2054 (i)
 
 
32,267,715
1,490,129
Commercial Mortgage Pass-Through Certificates, 2021-BN32, “XA”, 0.704%, 4/15/2054 (i)
 
 
17,897,506
461,765
Commercial Mortgage Pass-Through Certificates, 2021-BN35, “XA”, 1.022%, 6/15/2064 (i)
 
 
12,685,038
482,853
Commercial Mortgage Pass-Through Certificates, 2024-CBM, “A2”, 5.867%, 12/10/2041 (n)
 
 
1,395,974
1,396,641
EQT Trust, 2024-EXTR, “B”, 5.654%, 7/05/2041 (n)
 
 
1,503,054
1,517,828
Exeter Automobile Receivables Trust, 2026-2A, “A2”, 4.31%, 11/15/2028 
 
 
6,353,000
6,357,618
GLS Auto Select Receivables Trust, 2026-2A, “A2”, 4.04%, 11/15/2028 (n)
 
 
3,256,000
3,254,593
JP Morgan Mortgage Trust, 2026-NQM1, “A1”, 4.745%, 6/25/2066 (n)
 
 
1,562,276
1,547,077
KREF 2018-FT1 Ltd., “AS”, FLR, 5.042% ((SOFR - 1mo. + 0.11448%) + 1.3%), 2/15/2039 (n)
 
 
457,237
457,098
LoanCore 2021-CRE6 Ltd., “AS”, FLR, 5.391% ((SOFR - 1mo. + 0.11448%) + 1.65%), 11/15/2038 (n)
 
 
10,000,000
10,006,990
MF1 2021-FL7 Ltd., “A”, FLR, 4.82% ((SOFR - 1mo. + 0.11448%) + 1.08%), 10/16/2036 (n)
 
 
1,590,754
1,590,620
Morgan Stanley Capital I Trust, 2018-H4, “XA”, 0.798%, 12/15/2051 (i)
 
 
21,119,069
354,274
Morgan Stanley Capital I Trust, 2021-L5, “XA”, 1.178%, 5/15/2054 (i)
 
 
14,598,967
644,397
Morgan Stanley Capital I Trust, 2021-L6, “XA”, 1.141%, 6/15/2054 (i)
 
 
18,376,169
637,105
Morgan Stanley Capital I Trust, 2021-L7, “XA”, 1.054%, 10/15/2054 (i)
 
 
77,340,805
2,724,755
Morgan Stanley Residential Mortgage Loan Trust, 2026-NQM1, “A1”, 4.809%, 12/25/2070 (n)
 
 
1,748,748
1,731,643
Morgan Stanley Residential Mortgage Loan Trust, 2024-NQM3, “A1”, 5.044%, 7/25/2069 (n)
 
 
1,258,207
1,257,060
Morgan Stanley Residential Mortgage Loan Trust, 2025-NQM3, “A1”, 5.53%, 5/25/2070 (n)
 
 
2,192,162
2,198,799
Morgan Stanley Residential Mortgage Loan Trust, 2026-INV1, “A9”, FLR, 4.762% (SOFR - 1mo. + 1.15%), 2/25/2061 (n)
 
 
2,583,330
2,552,888
MTN Commercial Mortgage Trust, 2026-LPFX, 5.153%, 5/15/2043 (n)
 
 
641,696
641,934
New Residential Mortgage Loan Trust, 2026-NQM2, “A1”, 4.743%, 12/25/2065 (n)
 
 
4,879,405
4,827,594
New Residential Mortgage Loan Trust, 2026-NQM3, “A1”, 4.833%, 2/25/2066 (n)
 
 
9,828,493
9,737,588
OBX Trust, 2024-NQM1, “A2”, 6.253%, 11/25/2063 (n)
 
 
360,611
361,601
OBX Trust, 2025-NQM8, “A1”, 5.472%, 3/25/2065 (n)
 
 
1,744,872
1,751,344
Palmer Square Loan Funding 2024-3A Ltd., “A2R”, FLR, 4.8% (SOFR - 3mo. + 1.15%), 8/08/2032 (n)
 
 
1,530,612
1,530,115
Palmer Square Loan Funding 2025-2A Ltd., “A2”, FLR, 5.073% (SOFR - 3mo. + 1.4%), 7/15/2033 (n)
 
 
8,550,000
8,548,316
PFS Financing Corp., 2023-C, “B”, 5.91%, 10/15/2028 (n)
 
 
1,302,000
1,309,477
PFS Financing Corp., 2025-A, “A”, FLR, 4.293% (SOFR - 1mo. + 0.65%), 1/15/2029 (n)
 
 
4,611,000
4,615,357
PMT Loan Trust, 2025-INV10, “A36”, FLR, 4.962% (SOFR - 1mo. + 1.35%), 10/01/2056 (n)
 
 
2,075,137
2,076,740
PMT Loan Trust, 2026-CNF1, “A26”, FLR, 4.812% (SOFR - 1mo. + 1.2%), 1/25/2057 (n)
 
 
1,799,071
1,795,289
PMT Loan Trust, 2026-INV2, “A35”, FLR, 4.762% (SOFR - 1mo. + 1.15%), 1/25/2057 (n)
 
 
9,813,628
9,833,477
Provident Funding Mortgage Trust, 2024-1, “A3”, 5.5%, 12/25/2054 (n)
 
 
2,035,935
2,034,766
RCKT Trust, 2025-1A, “A”, 4.9%, 7/25/2034 (n)
 
 
512,679
513,605
Santander Drive Auto Receivables Trust, 2026-1, “A2”, 4.04%, 3/15/2029 
 
 
3,323,000
3,321,094
1
Portfolio of Investments (unaudited) – continued
Issuer
 
 
Shares/Par
Value ($)
Bonds – continued
Asset-Backed & Securitized – continued
Shackleton 2019-14A CLO Ltd., “BRR”, FLR, 5.225% (SOFR - 3mo. + 1.55%), 7/20/2034 (n)
 
$
6,434,263
$6,434,900
Verus Securitization Trust, 2024-1, “A2”, 5.915%, 1/25/2069 (n)
 
 
743,552
744,505
Wells Fargo Commercial Mortgage Trust, 2018-C48, “XA”, 0.927%, 1/15/2052 (i)(n)
 
 
11,810,565
216,169
Wells Fargo Commercial Mortgage Trust, 2021-C60, “XA”, 1.49%, 8/15/2054 (i)
 
 
19,323,819
1,104,026
 
 
 
$153,587,618
Consumer Services – 0.1%
Conservation Fund, 3.474%, 12/15/2029 
 
$
2,018,000
$1,918,406
Mortgage-Backed – 63.6%
Fannie Mae, 3%, 11/01/2028 - 9/01/2046 
 
$
6,665,831
$6,265,313
Fannie Mae, 3.5%, 1/25/2030 - 12/01/2047 
 
 
18,262,593
17,064,680
Fannie Mae, 2.5%, 11/01/2031 - 10/01/2046 
 
 
3,550,871
3,306,228
Fannie Mae, 3.5%, 12/25/2031 - 2/25/2036 (i)
 
 
635,951
41,703
Fannie Mae, 6.5%, 1/01/2032 - 10/01/2037 
 
 
342,406
356,687
Fannie Mae, 6%, 1/01/2033 - 12/01/2037 
 
 
1,005,859
1,037,526
Fannie Mae, 3%, 2/25/2033 - 1/25/2052 (i)
 
 
1,198,585
119,514
Fannie Mae, 5.5%, 5/01/2033 - 5/01/2044 
 
 
4,793,245
4,893,820
Fannie Mae, 5%, 11/01/2033 - 3/25/2042 
 
 
6,097,358
6,150,258
Fannie Mae, 4.5%, 3/01/2034 - 6/01/2044 
 
 
12,751,563
12,632,909
Fannie Mae, 4.177%, 4/25/2034 - 11/25/2046 
 
 
5,178,411
5,129,079
Fannie Mae, 4%, 9/01/2040 - 7/01/2047 
 
 
25,297,618
24,406,053
Fannie Mae, 1%, 3/25/2041 
 
 
1,260,913
1,110,467
Fannie Mae, 4.077%, 3/25/2041 
 
 
244,460
243,613
Fannie Mae, 2.25%, 4/25/2041 
 
 
1,018,675
981,571
Fannie Mae, 4.227%, 7/25/2041 
 
 
216,758
215,263
Fannie Mae, 1.75%, 9/25/2041 
 
 
723,133
700,236
Fannie Mae, 2.75%, 9/25/2042 
 
 
725,387
701,358
Fannie Mae, 0.000%, 10/25/2043 
 
 
1,911,434
1,431,814
Fannie Mae, 2%, 8/25/2044 - 4/25/2046 
 
 
1,639,003
1,527,091
Fannie Mae, 4.027%, 12/25/2045 
 
 
486,698
480,345
Fannie Mae, 2.273%, 9/25/2046 (i)
 
 
1,512,417
147,192
Fannie Mae, 2%, 9/25/2050 (i)
 
 
3,254,395
427,210
Fannie Mae, 4%, 9/25/2050 (i)
 
 
2,639,898
505,489
Fannie Mae, 2.5%, 2/25/2051 (i)
 
 
1,784,143
246,714
Fannie Mae, 5.062%, 11/25/2053 - 11/25/2054 
 
 
7,692,215
7,789,975
Fannie Mae, 5.512%, 11/25/2053 
 
 
2,590,535
2,668,352
Fannie Mae, 5.612%, 11/25/2053 
 
 
7,499,385
7,743,512
Fannie Mae, 4.512%, 12/25/2053 
 
 
1,462,593
1,471,452
Fannie Mae, 6.612%, 7/25/2054 
 
 
2,548,433
2,642,200
Fannie Mae, 4.762%, 10/25/2054 
 
 
2,734,977
2,749,206
Fannie Mae, 4.562%, 11/25/2054 
 
 
5,580,179
5,605,254
Fannie Mae, 4.962%, 11/25/2054 
 
 
9,131,242
9,219,320
Fannie Mae, 4.612%, 12/25/2054 
 
 
7,849,143
7,906,601
Fannie Mae, 5.012%, 12/25/2054 
 
 
6,090,352
6,158,102
Fannie Mae, 5.112%, 12/25/2054 
 
 
9,137,381
9,247,244
Fannie Mae, 4.912%, 1/25/2055 
 
 
7,573,678
7,638,741
Fannie Mae, 6.052%, 3/25/2055 
 
 
3,567,096
3,580,226
Fannie Mae, UMBS, 2.5%, 5/01/2036 - 8/01/2052 
 
 
86,004,110
73,315,389
Fannie Mae, UMBS, 5.5%, 10/01/2038 - 5/01/2055 
 
 
25,414,989
25,588,889
Fannie Mae, UMBS, 4.5%, 2/01/2041 - 10/01/2055 
 
 
6,208,448
6,061,188
Fannie Mae, UMBS, 1.5%, 2/01/2042 - 3/01/2051 
 
 
1,306,905
1,032,712
Fannie Mae, UMBS, 2%, 2/01/2042 - 3/01/2052 
 
 
43,725,277
35,591,375
Fannie Mae, UMBS, 3.5%, 5/01/2049 - 2/01/2052 
 
 
1,647,362
1,517,409
Fannie Mae, UMBS, 3%, 6/01/2051 - 8/01/2052 
 
 
14,453,874
12,777,141
Fannie Mae, UMBS, 4%, 8/01/2051 - 2/01/2053 
 
 
4,908,982
4,652,894
Fannie Mae, UMBS, 5%, 9/01/2052 - 6/01/2056 
 
 
7,728,981
7,609,218
Fannie Mae, UMBS, 6%, 2/01/2053 - 12/01/2054 
 
 
12,671,830
12,992,412
Freddie Mac, 2.57%, 7/25/2026 
 
 
19,446,587
19,379,566
2
Portfolio of Investments (unaudited) – continued
Issuer
 
 
Shares/Par
Value ($)
Bonds – continued
Mortgage-Backed – continued
Freddie Mac, 3.12%, 9/25/2026 
 
$
10,875,726
$10,826,194
Freddie Mac, 2.525%, 10/25/2026 
 
 
10,679,353
10,622,298
Freddie Mac, 3.413%, 12/25/2026 
 
 
16,429,203
16,345,279
Freddie Mac, 1.373%, 3/25/2027 (i)
 
 
5,583,000
49,903
Freddie Mac, 3.243%, 4/25/2027 
 
 
10,090,226
10,008,990
Freddie Mac, 3.117%, 6/25/2027 
 
 
20,333,810
20,132,100
Freddie Mac, 0.559%, 7/25/2027 (i)
 
 
98,090,842
457,908
Freddie Mac, 0.401%, 8/25/2027 (i)
 
 
75,703,157
326,334
Freddie Mac, 1.47%, 9/25/2027 
 
 
4,600,000
4,447,371
Freddie Mac, 3.286%, 11/25/2027 
 
 
6,876,682
6,784,944
Freddie Mac, 0.355%, 12/25/2027 (i)
 
 
1,295,192
6,684
Freddie Mac, 1.603%, 12/25/2027 
 
 
8,199,693
7,895,774
Freddie Mac, 0.294%, 1/25/2028 (i)
 
 
134,862,400
580,718
Freddie Mac, 0.3%, 1/25/2028 (i)
 
 
56,495,986
246,520
Freddie Mac, 0.114%, 2/25/2028 (i)
 
 
157,287,057
352,134
Freddie Mac, 0.102%, 4/25/2028 (i)
 
 
105,411,275
252,987
Freddie Mac, 3.9%, 4/25/2028 
 
 
1,867,674
1,855,219
Freddie Mac, 0.424%, 10/25/2028 (i)
 
 
39,420,879
382,268
Freddie Mac, 0.415%, 5/25/2029 (i)
 
 
56,014,587
654,771
Freddie Mac, 0.816%, 7/25/2029 (i)
 
 
31,354,116
750,175
Freddie Mac, 1.08%, 7/25/2029 (i)
 
 
18,572,289
548,117
Freddie Mac, 1.133%, 8/25/2029 (i)
 
 
32,692,296
1,045,898
Freddie Mac, 0.57%, 1/25/2030 (i)
 
 
19,111,703
364,300
Freddie Mac, 1.313%, 1/25/2030 (i)
 
 
26,051,209
1,080,995
Freddie Mac, 1.582%, 1/25/2030 (i)
 
 
19,061,018
941,862
Freddie Mac, 1.797%, 4/25/2030 (i)
 
 
14,430,646
908,421
Freddie Mac, 1.839%, 4/25/2030 (i)
 
 
20,077,463
1,284,217
Freddie Mac, 0.412%, 5/25/2030 (i)
 
 
25,620,819
389,606
Freddie Mac, 1.666%, 5/25/2030 (i)
 
 
12,033,779
734,929
Freddie Mac, 1.798%, 5/25/2030 (i)
 
 
26,880,424
1,730,298
Freddie Mac, 5.5%, 6/01/2030 - 9/01/2041 
 
 
2,070,563
2,126,540
Freddie Mac, 1.107%, 6/25/2030 (i)
 
 
19,705,936
750,108
Freddie Mac, 1.34%, 6/25/2030 (i)
 
 
11,124,134
539,365
Freddie Mac, 1.367%, 6/25/2030 (i)
 
 
28,999,694
1,318,141
Freddie Mac, 1.597%, 8/25/2030 (i)
 
 
10,235,210
608,100
Freddie Mac, 1.168%, 9/25/2030 (i)
 
 
6,568,138
295,206
Freddie Mac, 1.079%, 11/25/2030 (i)
 
 
13,158,725
569,336
Freddie Mac, 0.316%, 1/25/2031 (i)
 
 
49,437,128
556,964
Freddie Mac, 0.536%, 1/25/2031 - 9/25/2031 (i)
 
 
120,996,513
2,898,066
Freddie Mac, 0.779%, 1/25/2031 (i)
 
 
19,512,958
653,606
Freddie Mac, 0.935%, 1/25/2031 (i)
 
 
14,681,587
559,749
Freddie Mac, 0.356%, 2/25/2031 (i)
 
 
18,431,877
343,583
Freddie Mac, 0.507%, 3/25/2031 (i)
 
 
39,782,799
789,195
Freddie Mac, 0.731%, 3/25/2031 (i)
 
 
17,260,719
557,715
Freddie Mac, 1.213%, 5/25/2031 (i)
 
 
7,120,528
375,347
Freddie Mac, 0.937%, 7/25/2031 (i)
 
 
11,674,001
510,002
Freddie Mac, 1.215%, 7/25/2031 (i)
 
 
22,560,568
1,256,132
Freddie Mac, 0.505%, 8/25/2031 (i)
 
 
14,782,948
330,494
Freddie Mac, 0.854%, 9/25/2031 (i)
 
 
48,419,608
1,917,257
Freddie Mac, 0.349%, 11/25/2031 (i)
 
 
73,361,326
1,253,980
Freddie Mac, 0.496%, 12/25/2031 (i)
 
 
73,957,916
1,736,414
Freddie Mac, 0.567%, 12/25/2031 (i)
 
 
12,187,459
319,589
Freddie Mac, 0.765%, 2/25/2032 (i)
 
 
49,680,895
1,930,177
Freddie Mac, 0.32%, 6/25/2032 (i)
 
 
116,203,070
2,110,283
Freddie Mac, 4.207%, 11/15/2032 
 
 
32,337
32,287
Freddie Mac, 0.154%, 11/25/2032 (i)
 
 
74,026,378
863,318
Freddie Mac, 0.266%, 5/25/2033 (i)
 
 
64,115,960
1,246,568
Freddie Mac, 3.5%, 8/15/2033 - 10/25/2058 
 
 
20,629,322
19,559,963
Freddie Mac, 0.129%, 8/25/2033 (i)
 
 
78,666,400
893,808
3
Portfolio of Investments (unaudited) – continued
Issuer
 
 
Shares/Par
Value ($)
Bonds – continued
Mortgage-Backed – continued
Freddie Mac, 0.177%, 10/25/2033 (i)
 
$
75,772,703
$1,153,397
Freddie Mac, 5%, 5/01/2034 - 12/01/2044 
 
 
5,691,495
5,743,935
Freddie Mac, 6%, 8/01/2034 - 10/01/2038 
 
 
2,010,144
2,082,449
Freddie Mac, 0.905%, 9/25/2034 (i)
 
 
9,883,118
647,098
Freddie Mac, 0.056%, 1/25/2035 (i)
 
 
119,066,272
1,023,851
Freddie Mac, 0.246%, 1/25/2035 (i)
 
 
47,468,092
1,025,382
Freddie Mac, 0.045%, 12/25/2035 (i)
 
 
114,495,340
997,003
Freddie Mac, 5.5%, 2/15/2036 (i)
 
 
215,023
32,373
Freddie Mac, 6.5%, 5/01/2037 
 
 
72,953
76,317
Freddie Mac, 4%, 8/01/2037 - 4/01/2044 
 
 
2,789,819
2,701,034
Freddie Mac, 3%, 1/01/2038 - 2/25/2059 
 
 
12,054,527
11,007,658
Freddie Mac, 4.5%, 7/01/2039 - 5/01/2042 
 
 
1,956,717
1,940,127
Freddie Mac, 4.5%, 12/15/2040 (i)
 
 
28,720
2,630
Freddie Mac, 1.75%, 8/15/2041 
 
 
548,406
523,224
Freddie Mac, 4.157%, 11/15/2043 - 8/15/2046 
 
 
1,460,549
1,445,565
Freddie Mac, 2.5%, 11/25/2050 - 3/25/2051 (i)
 
 
10,837,086
1,752,645
Freddie Mac, 3%, 10/25/2052 (i)
 
 
1,838,023
294,588
Freddie Mac, 4.812%, 9/25/2053 
 
 
8,772,622
8,876,143
Freddie Mac, 5.062%, 10/25/2053 
 
 
6,868,306
7,017,768
Freddie Mac, 5.842%, 12/25/2053 
 
 
3,129,210
3,139,655
Freddie Mac, 4.712%, 1/25/2054 - 9/25/2054 
 
 
8,727,524
8,803,608
Freddie Mac, 4.912%, 1/25/2054 - 12/25/2054 
 
 
9,339,263
9,442,174
Freddie Mac, 5.112%, 12/25/2054 
 
 
10,974,813
11,110,720
Freddie Mac, 6.062%, 1/25/2055 
 
 
2,047,825
2,067,172
Freddie Mac, 7.562%, 9/25/2055 
 
 
806,734
838,498
Freddie Mac, 2.343%, 8/15/2057 (i)
 
 
2,834,809
345,890
Freddie Mac, 0.225%, 3/25/2061 (i)
 
 
64,696,386
735,274
Freddie Mac, 3.25%, 11/25/2061 
 
 
3,922,478
3,624,295
Freddie Mac, UMBS, 2.5%, 3/01/2037 - 9/01/2052 
 
 
22,034,591
18,634,711
Freddie Mac, UMBS, 4.5%, 2/01/2041 - 8/01/2055 
 
 
33,898,239
33,516,113
Freddie Mac, UMBS, 2%, 2/01/2042 - 3/01/2052 
 
 
16,300,537
13,415,915
Freddie Mac, UMBS, 3.5%, 12/01/2046 - 5/01/2052 
 
 
2,211,768
2,042,570
Freddie Mac, UMBS, 3%, 2/01/2050 - 8/01/2052 
 
 
26,661,363
23,386,424
Freddie Mac, UMBS, 1.5%, 10/01/2051 - 11/01/2051 
 
 
487,370
372,460
Freddie Mac, UMBS, 4%, 5/01/2052 
 
 
3,583,039
3,384,969
Freddie Mac, UMBS, 5%, 11/01/2052 - 6/01/2056 
 
 
30,514,165
30,065,194
Freddie Mac, UMBS, 5.5%, 12/01/2052 - 7/01/2055 
 
 
14,891,150
15,001,937
Freddie Mac, UMBS, 6%, 2/01/2053 - 2/01/2055 
 
 
9,570,407
9,822,847
Freddie Mac, UMBS, 6.5%, 4/01/2054 - 11/01/2054 
 
 
3,470,187
3,629,988
Ginnie Mae, 3.5%, 8/20/2029 - 1/20/2043 (i)
 
 
4,613,859
575,152
Ginnie Mae, 5.5%, 3/15/2033 - 10/20/2053 
 
 
2,220,810
2,251,954
Ginnie Mae, 4.5%, 7/20/2033 - 10/20/2052 
 
 
22,907,318
22,280,843
Ginnie Mae, 5.649%, 8/20/2034 
 
 
530,810
537,940
Ginnie Mae, 4%, 5/16/2039 - 9/20/2055 
 
 
11,270,839
10,560,183
Ginnie Mae, 5%, 8/20/2039 - 4/20/2053 
 
 
5,045,646
5,039,406
Ginnie Mae, 4%, 12/20/2039 - 9/20/2047 (i)
 
 
1,430,162
220,343
Ginnie Mae, 1.683%, 5/20/2041 (i)
 
 
2,436,783
192,187
Ginnie Mae, 3.817%, 9/20/2041 
 
 
5,996,908
5,831,434
Ginnie Mae, 2.41%, 11/16/2041 (i)
 
 
1,569,525
51,815
Ginnie Mae, 3.5%, 12/15/2041 - 7/20/2043 
 
 
5,548,342
5,194,416
Ginnie Mae, 2.5%, 6/20/2042 - 1/20/2066 
 
 
20,661,795
17,723,080
Ginnie Mae, 3%, 2/20/2043 - 10/20/2052 
 
 
24,722,466
22,078,832
Ginnie Mae, 2.433%, 4/20/2047 (i)
 
 
435,272
47,300
Ginnie Mae, 2%, 11/20/2050 (i)
 
 
173,261
18,939
Ginnie Mae, 2.5%, 2/20/2051 (i)
 
 
2,128,073
286,987
Ginnie Mae, 2%, 1/20/2052 - 11/20/2052 
 
 
32,276,782
26,487,825
Ginnie Mae, 4.625%, 8/20/2053 - 12/20/2064 
 
 
21,937,717
22,032,439
Ginnie Mae, 4.875%, 8/20/2053 - 4/20/2055 
 
 
11,988,048
12,082,838
Ginnie Mae, 4.975%, 9/20/2053 - 10/20/2053 
 
 
18,085,960
18,331,000
4
Portfolio of Investments (unaudited) – continued
Issuer
 
 
Shares/Par
Value ($)
Bonds – continued
Mortgage-Backed – continued
Ginnie Mae, 5.025%, 9/20/2053 
 
$
9,610,173
$9,763,073
Ginnie Mae, 4.925%, 10/20/2053 
 
 
9,093,368
9,216,292
Ginnie Mae, 4.275%, 11/20/2053 - 8/20/2074 
 
 
15,068,459
15,075,885
Ginnie Mae, 4.725%, 11/20/2053 - 2/20/2054 
 
 
24,298,718
24,530,622
Ginnie Mae, 4.825%, 12/20/2053 - 2/20/2066 
 
 
38,428,390
38,738,263
Ginnie Mae, 4.675%, 2/20/2054 - 10/20/2054 
 
 
11,768,701
11,841,013
Ginnie Mae, 4.575%, 3/20/2054 
 
 
8,206,623
8,246,158
Ginnie Mae, 7.575%, 5/20/2055 
 
 
1,906,971
1,952,818
Ginnie Mae, 6.137%, 6/20/2055 
 
 
3,596,233
3,613,293
Ginnie Mae, 6.212%, 6/20/2055 
 
 
1,750,090
1,680,998
Ginnie Mae, 1.725%, 7/20/2055 (i)
 
 
3,499,606
167,470
Ginnie Mae, 6%, 11/20/2055 
 
 
2,353,099
2,413,105
Ginnie Mae, 4.355%, 2/20/2056 
 
 
6,639,457
6,636,988
Ginnie Mae, 4.175%, 12/20/2060 
 
 
6,179
6,164
Ginnie Mae, 4.255%, 3/20/2061 - 10/20/2064 
 
 
161,263
161,047
Ginnie Mae, 2.09%, 12/20/2062 (i)
 
 
3,151,493
141,281
Ginnie Mae, 4.225%, 4/20/2063 - 11/20/2067 
 
 
1,076,927
1,074,964
Ginnie Mae, 4.775%, 3/20/2064 
 
 
877,325
885,386
Ginnie Mae, 4.455%, 7/20/2064 
 
 
471,697
472,877
Ginnie Mae, 4.375%, 3/20/2065 
 
 
26,646
26,684
Ginnie Mae, 4.425%, 8/20/2065 - 2/20/2066 
 
 
21,796,326
21,727,595
Ginnie Mae, 4.475%, 9/20/2065 
 
 
9,304,335
9,316,451
Ginnie Mae, 2.266%, 3/20/2066 (i)
 
 
1,029,783
35,210
Ginnie Mae, 4.525%, 10/20/2066 
 
 
622,265
624,618
Ginnie Mae, 4.545%, 10/20/2066 
 
 
1,493,742
1,500,396
Ginnie Mae, 4.541%, 1/20/2067 
 
 
1,487,099
1,494,561
Ginnie Mae, 4.391%, 2/20/2067 
 
 
1,153,538
1,157,020
Ginnie Mae, 4.505%, 3/20/2067 
 
 
2,668,688
2,677,982
Ginnie Mae, 4.075%, 5/20/2067 
 
 
7,868,668
7,866,628
Ginnie Mae, 5.281%, 7/20/2067 
 
 
3,210,179
3,236,116
Ginnie Mae, 4.125%, 8/20/2067 
 
 
10,116,790
10,119,345
Ginnie Mae, 4.298%, 4/20/2068 
 
 
5,486,507
5,493,632
Ginnie Mae, 4.025%, 12/20/2071 
 
 
1,920,221
1,917,475
Ginnie Mae, 4.55%, 12/20/2071 
 
 
578,647
575,738
Ginnie Mae, 3.625%, 11/20/2074 
 
 
2,179,351
2,161,633
Ginnie Mae, TBA, 5%, 6/22/2056 
 
 
7,275,000
7,183,470
UMBS, TBA, 2%, 6/11/2056 
 
 
44,775,000
35,805,975
UMBS, TBA, 5.5%, 6/11/2056 
 
 
8,525,000
8,562,625
UMBS, TBA, 6%, 6/11/2056 
 
 
32,200,000
32,878,459
UMBS, TBA, 1.5%, 6/25/2056 
 
 
5,050,000
3,851,410
UMBS, TBA, 2.5%, 6/25/2056 
 
 
7,650,000
6,400,007
 
 
 
$1,228,748,259
U.S. Government Agencies and Equivalents – 0.1%
Small Business Administration, 2.21%, 2/01/2033 
 
$
366,780
$343,712
Small Business Administration, 2.22%, 3/01/2033 
 
 
624,944
583,038
Small Business Administration, 3.15%, 7/01/2033 
 
 
576,917
553,145
Small Business Administration, 3.16%, 8/01/2033 
 
 
231,375
220,980
Small Business Administration, 3.62%, 9/01/2033 
 
 
194,114
188,586
 
 
 
$1,889,461
U.S. Treasury Obligations – 31.1%
U.S. Treasury Bonds, 6.375%, 8/15/2027 
 
$
2,309,000
$2,375,203
U.S. Treasury Bonds, 4.375%, 2/15/2038 
 
 
2,078,000
2,056,733
U.S. Treasury Bonds, 3.125%, 2/15/2043 
 
 
9,748,800
7,752,200
U.S. Treasury Bonds, 2.875%, 5/15/2043 
 
 
27,528,200
21,005,307
U.S. Treasury Bonds, 4.75%, 11/15/2043 
 
 
11,168,000
10,936,788
U.S. Treasury Bonds, 2.5%, 2/15/2045 
 
 
97,983,000
68,186,217
U.S. Treasury Bonds, 4.75%, 2/15/2045 
 
 
36,531,000
35,570,634
5
Portfolio of Investments (unaudited) – continued
Issuer
 
 
Shares/Par
Value ($)
Bonds – continued
U.S. Treasury Obligations – continued
U.S. Treasury Bonds, 5%, 5/15/2045 
 
$
4,336,000
$4,353,446
U.S. Treasury Bonds, 4.625%, 5/15/2054 
 
 
11,176,000
10,536,873
U.S. Treasury Bonds, 4.625%, 2/15/2055 
 
 
11,722,000
11,053,480
U.S. Treasury Bonds, 4.75%, 8/15/2055 
 
 
6,088,000
5,861,840
U.S. Treasury Bonds, 5%, 5/15/2056 
 
 
12,550,400
12,587,659
U.S. Treasury Notes, 3.375%, 11/30/2027 
 
 
21,069,000
20,887,115
U.S. Treasury Notes, 3.375%, 12/31/2027 
 
 
7,056,000
6,989,850
U.S. Treasury Notes, 2.75%, 2/15/2028 
 
 
54,157,000
53,046,359
U.S. Treasury Notes, 3.625%, 3/31/2028 (f)
 
 
65,576,000
65,140,535
U.S. Treasury Notes, 1%, 7/31/2028 
 
 
32,248,000
30,247,616
U.S. Treasury Notes, 2.375%, 5/15/2029 
 
 
19,515,500
18,612,908
U.S. Treasury Notes, 3.625%, 8/31/2029 
 
 
27,900,000
27,518,555
U.S. Treasury Notes, 4.375%, 12/31/2029 
 
 
7,900,000
7,974,371
U.S. Treasury Notes, 3.5%, 4/30/2030 (f)
 
 
18,675,000
18,266,484
U.S. Treasury Notes, 4.125%, 8/31/2030 
 
 
37,647,000
37,642,588
U.S. Treasury Notes, 1.625%, 5/15/2031 (f)
 
 
41,833,000
37,139,860
U.S. Treasury Notes, 1.375%, 11/15/2031 (f)
 
 
11,425,300
9,869,049
U.S. Treasury Notes, 4.25%, 8/15/2035 
 
 
31,630,000
31,240,803
U.S. Treasury Notes, TIPS, 1.25%, 4/15/2031 
 
 
45,332,645
44,597,596
 
 
 
$601,450,069
Total Bonds
$1,987,593,813
Mutual Funds (h) – 2.1%
Money Market Funds – 2.1%
MFS Institutional Money Market Portfolio, 3.69% (v)
 
 
41,525,461
$41,529,614
 
Other Assets, Less Liabilities – (5.0)%
(97,513,694
)
Net Assets – 100.0%
$1,931,609,733
 
(f)
All or a portion of the security has been segregated as collateral for open futures contracts, cleared swap agreements, and mortgage-backed securities/
TBAs.
(h)
An affiliated issuer, which may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under
common control. At period end, the aggregate values of the fund's investments in affiliated issuers and in unaffiliated issuers were $41,529,614 and
$1,987,593,813, respectively.
(i)
Interest only security for which the fund receives interest on notional principal (Par amount). Par amount shown is the notional principal and does not reflect
the cost of the security.
(n)
Securities exempt from registration under Rule 144A of the Securities Act of 1933. These securities may be sold in the ordinary course of business in
transactions exempt from registration, normally to qualified institutional buyers. At period end, the aggregate value of these securities was $124,824,654,
representing 6.5% of net assets.
(v)
Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the
annualized seven-day yield of the fund at period end.
 
The following abbreviations are used in this report and are defined:
CLO
Collateralized Loan Obligation
CPI-U
Consumer Price Index - Urban Consumers
FLR
Floating Rate. Interest rate resets periodically based on the parenthetically disclosed reference rate plus a spread (if any). The period-end rate
reported may not be the current rate. All reference rates are USD unless otherwise noted.
SOFR
Secured Overnight Financing Rate
TBA
To Be Announced
TIPS
Treasury Inflation Protected Security
UMBS
Uniform Mortgage-Backed Security
 
6
Portfolio of Investments (unaudited) – continued
Derivative Contracts at 5/31/26
Futures Contracts
Description
Long/
Short
Currency
Contracts
Notional
Amount
Expiration
Date
Value/Unrealized
Appreciation
(Depreciation)
Asset Derivatives
Interest Rate Futures 
U.S. Treasury Note 10 yr
Long
USD
1,760
$193,297,500
September – 2026
$1,192,229
U.S. Treasury Note 2 yr
Long
USD
2,500
516,406,250
September – 2026
1,002,041
U.S. Treasury Note 5 yr
Long
USD
2,964
317,773,220
September – 2026
1,522,078
U.S. Treasury Ultra Bond 30 yr
Long
USD
41
4,690,656
September – 2026
66,260
U.S. Treasury Ultra Note 10 yr
Long
USD
484
54,245,813
September – 2026
421,443
 
 
$4,204,051
 
Cleared Swap Agreements
Maturity
Date
Notional
Amount
Counterparty
Cash Flows
to Receive/
Frequency
Cash Flows
to Pay/
Frequency
Unrealized
Appreciation
(Depreciation)
Net
Unamortized
Upfront
Payments
(Receipts)
Value
Asset Derivatives
Interest Rate Swaps 
11/03/27
USD
100,992,000
centrally cleared
1-day SOFR / Annually
3.389% / Annually
$844,527
$—
$844,527
11/05/27
USD
100,309,000
centrally cleared
1-day SOFR / Annually
3.387% / Annually
853,069
—
853,069
11/26/27
USD
100,742,000
centrally cleared
1-day SOFR / Annually
3.2845% / Annually
1,034,620
—
1,034,620
5/01/28
USD
194,750,000
centrally cleared
1-day SOFR / Annually
3.7185% / Annually
695,212
—
695,212
1/09/29
USD
100,500,000
centrally cleared
1-day SOFR / Annually
3.35% / Annually
1,353,960
—
1,353,960
4/30/29
USD
97,620,000
centrally cleared
1-day SOFR / Annually
3.637% / Annually
573,895
—
573,895
1/14/31
USD
60,400,000
centrally cleared
1-day SOFR / Annually
3.5105% / Annually
924,326
—
924,326
 
 
 
 
 
 
$6,279,609
$—
$6,279,609
Liability Derivatives
Inflation Swaps 
5/21/46
USD
14,845,000
centrally cleared
CPI-U / At Maturity
2.5185% / At Maturity
$(102,720
)
$—
$(102,720
)
5/20/56
USD
19,130,000
centrally cleared
CPI-U / At Maturity
2.463% / At Maturity
(134,545
)
—
(134,545
)
 
 
 
 
 
 
$(237,265
)
$—
$(237,265
)
At May 31, 2026, the fund had liquid securities collateral with an aggregate value of $25,657,755 to cover any collateral or margin obligations for certain derivative contracts.
See attached supplemental information. For more information see notes to financial statements as disclosed in the most recent semiannual or annual report.
7
Supplemental Information
5/31/26 (unaudited)
The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial
Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services - Investment Companies.
(1) Investment Valuations
Subject to its oversight, the fund's Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments to MFS as the fund's adviser, pursuant to the fund’s valuation policy and procedures which have been adopted by the adviser and approved by the Board. In accordance with Rule 2a-5 under the Investment Company Act of 1940, the Board of Trustees designated the adviser as the “valuation designee” of the fund. If the adviser, as valuation designee, determines that reliable market quotations are not readily available for an investment, the investment is valued at fair value as determined in good faith by the adviser in accordance with the adviser’s fair valuation policy and procedures.
Under the fund's valuation policy and procedures, debt instruments and floating rate loans, including restricted debt instruments, are
generally valued at an evaluated or composite bid as provided by a third-party pricing service. Short-term instruments with a maturity at
issuance of 60 days or less may be valued at amortized cost, which approximates market value. Futures contracts are generally valued at last posted settlement price on their primary exchange as provided by a third-party pricing service. Futures contracts for which there were no trades that day for a particular position are generally valued at the closing bid quotation on their primary exchange as provided by a
third-party pricing service. Swap agreements are generally valued using valuations provided by a third-party pricing service, which for cleared
swaps includes an evaluation of any trading activity at the clearinghouses. Open-end investment companies are generally valued at net asset
value per share. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.
Under the fund’s valuation policy and procedures, market quotations are not considered to be readily available for debt instruments, floating rate loans, and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services or otherwise determined by the adviser in accordance with the adviser’s fair valuation policy and procedures. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. In determining values, third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, spreads and other market data. Pricing services generally value debt instruments assuming orderly transactions of institutional round lot sizes, but a fund may hold or transact in such securities in smaller, odd lot sizes. In instances where a fund holds an odd lot size position in a debt instrument, such position will typically be valued using the pricing agent’s institutional round lot price for the debt instrument. Odd lots may trade at lower prices than institutional round lots, and the fund may receive different prices when it sells odd lot positions than it would receive for sales of institutional round lot positions. An investment may also be valued at fair value if the adviser determines that the investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halt of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net
asset value per share.
Various inputs are used in determining the value of the fund's assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment's level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund's assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk).
8
Supplemental Information (unaudited) – continued
Level 3 includes significant unobservable inputs, which may include the adviser's own assumptions in determining the fair value of investments. Other financial instruments are derivative instruments, such as futures contracts and swap agreements. The following is a summary of the levels used as of May 31, 2026 in valuing the fund's assets and liabilities: 
Financial Instruments
Level 1
Level 2
Level 3
Total
U.S. Treasury Bonds & U.S. Government Agencies & Equivalents
$—
$603,339,530
$—
$603,339,530
U.S. Corporate Bonds
—
1,918,406
—
1,918,406
Residential Mortgage-Backed Securities
—
1,271,198,630
—
1,271,198,630
Commercial Mortgage-Backed Securities
—
43,776,074
—
43,776,074
Asset-Backed Securities (including CDOs)
—
67,361,173
—
67,361,173
Investment Companies
41,529,614
—
—
41,529,614
Total
$41,529,614
$1,987,593,813
$—
$2,029,123,427
Other Financial Instruments
Futures Contracts – Assets
$4,204,051
$—
$—
$4,204,051
Swap Agreements – Assets
—
6,279,609
—
6,279,609
Swap Agreements – Liabilities
—
(237,265
)
—
(237,265
)
(2) Investments in Affiliated Issuers
An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. The following were affiliated issuers for the period ended May 31, 2026:
 
Affiliated Issuers
Beginning
Value
Purchases
Sales
Proceeds
Realized
Gain
(Loss)
Change in
Unrealized
Appreciation or
Depreciation
Ending
Value
MFS Institutional Money Market Portfolio
$66,351,406
$363,490,374
$388,322,215
$11,169
$(1,120
)
$41,529,614
 
Affiliated Issuers
Dividend
Income
Capital Gain
Distributions
MFS Institutional Money Market Portfolio
$647,773
$—
9