v3.26.1
Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Tables)
 6 Months Ended
Jun. 30, 2026
Investments, Debt and Equity Securities [Abstract]  
Schedule of Fair Value of APS's Nuclear Decommissioning Trust Fund Assets
The following tables present the unrealized gains and losses based on the original cost of the investment and summarize the fair value of the nuclear decommissioning trusts and other special use fund assets (dollars in thousands): 
June 30, 2026
Fair ValueTotal
Unrealized
Gains		Total
Unrealized
Losses
Investment Type:Nuclear Decommissioning TrustsOther Special Use FundsTotal
Equity securities$563,582 $54,944 $618,526 $478,401 (d)$(6)
Available for sale-fixed income securities895,405 369,957 1,265,362 (a)9,369 (16,048)
Other8,971 6,968 15,939 (b)481 — 
Total$1,467,958 $431,869 $1,899,827 (c)$488,251 $(16,054)
(a)As of June 30, 2026, the amortized cost basis of these available-for-sale investments is $1,272 million.
(b)Primarily represents net pending securities sales and purchases.
(c)All amounts pertain to APS, with the exception of $42.2 million of other special use fund investments in equity securities and $4.0 million of other, relating to investments held by the Captive.
(d)All amounts pertain to APS, with the exception of $3.7 million of unrealized gains relating to investments held by the Captive.
December 31, 2025
Fair ValueTotal
Unrealized
Gains		Total
Unrealized
Losses
Investment Type:Nuclear Decommissioning TrustsOther Special Use FundsTotal
Equity securities$519,562 $62,573 $582,135 $433,044 (d)$(1)
Available for sale-fixed income securities898,403 369,055 1,267,458 (a)18,765 (14,993)
Other(3,799)3,199 (600)(b)— — 
Total$1,414,166 $434,827 $1,848,993 (c)$451,809 $(14,994)
(a)As of December 31, 2025, the amortized cost basis of these available-for-sale investments is $1,265 million.
(b)Represents net pending securities sales and purchases.
(c)All amounts pertain to APS, with the exception of $40.3 million of other special use fund investments in equity securities relating to investments held by the Captive.
(d)All amounts pertain to APS, with the exception of $3.2 million of unrealized gains relating to investments held by the Captive.
Schedule of Realized Gains and Losses and Proceeds from the Sale of Securities by the Nuclear Decommissioning Trust Funds
The following table sets forth realized gains and losses relating to the sale and maturity of available-for-sale debt securities and equity securities, and the proceeds from the sale and maturity of these investment securities (dollars in thousands):
Three Months Ended June 30,
Nuclear Decommissioning TrustsOther Special Use FundsTotal
2026
Realized gains$2,505 $154 $2,659 
Realized losses$(4,656)$— $(4,656)
Proceeds from the sale of securities (a)$403,032 $82,361 (b)$485,393 
2025
Realized gains$1,702 $— $1,702 
Realized losses$(2,611)$— $(2,611)
Proceeds from the sale of securities (a)$342,313 $91,517 (c)$433,830 
(a)    Proceeds are reinvested in the nuclear decommissioning trusts and other special use funds, excluding investment fees and amounts reimbursed to the Company for active union employee medical claims from the active union employee medical account.
(b)    All amounts pertain to APS, with the exception of $5.8 million of other special use fund proceeds from the sale of securities relating to investments held by the Captive.
(c)    All amounts pertain to APS, with the exception of $25.2 million of other special use fund proceeds from the sale of securities relating to the Captive.
Six Months Ended June 30,
Nuclear Decommissioning TrustsOther Special Use FundsTotal
2026
Realized gains$7,225 $170 $7,395 
Realized losses$(7,453)$— $(7,453)
Proceeds from the sale of securities (a)$850,915 $146,712 (b)$997,627 
2025
Realized gains$3,360 $— $3,360 
Realized losses$(5,372)$— $(5,372)
Proceeds from the sale of securities (a)$758,914 $160,730 (c)$919,644 

(a)    Proceeds are reinvested in the nuclear decommissioning trusts and other special use funds, excluding investment fees and amounts reimbursed to the Company for active union employee medical claims from the active union employee medical account.
(b)    All amounts pertain to APS, with the exception of $5.8 million of other special use fund proceeds from the sale of securities relating to investments held by the Captive.
(c)    All amounts pertain to APS, with the exception of $50.5 million of other special use fund proceeds from the sale of securities relating to investments held by the Captive.
Schedule of Fair Value of Fixed Income Securities, Summarized by Contractual Maturities
The fair value of fixed income securities summarized by contractual maturities as of June 30, 2026 is as follows (dollars in thousands):
Nuclear Decommissioning TrustsCoal Reclamation Escrow AccountActive Union Employee Medical AccountTotal
Less than one year$28,346 $101,521 $39,940 $169,807 
1 year – 5 years282,988 56,420 155,655 495,063 
5 years – 10 years212,249 — 16,421 228,670 
Greater than 10 years371,822 — — 371,822 
Total$895,405 $157,941 $212,016 $1,265,362