N-MFP3 0001060517 XXXXXXXX 2026-06-30 UBS Series Funds 0001060517 54930058UKPXVB81RJ71 UBS Select 100% US Treasury Preferred Fund 529900FTKZBAKZ4ON106 S000084283 2 N N 333-52965 UBS ASSET MANAGEMENT (AMERICAS) LLC 801-34910 Ernst & Young LLP New York NY UBS ASSET MANAGEMENT (AMERICAS) LLC BNY Mellon Investment Servicing (US) Inc. 0000849542 084-01761 Y 0001403166 100 [percent symbol] US Treasury Master Fund S000085171 N N Government N Y 1 1 18048578844.10 18048578844.10 0.9997 0.9997 2026-06-01 17681871012.58 17681871012.58 0.9997 0.9997 2026-06-02 18036022912.70 18036022912.70 0.9997 0.9997 2026-06-03 17784758973.42 17784758973.42 0.9997 0.9997 2026-06-04 17936060263.58 17936060263.58 0.9997 0.9997 2026-06-05 18262541192.33 18262541192.33 0.9997 0.9997 2026-06-08 17899583128.36 17899583128.36 0.9997 0.9997 2026-06-09 18049918078.00 18049918078.00 0.9997 0.9997 2026-06-10 17768090302.42 17768090302.42 0.9997 0.9997 2026-06-11 17741841165.55 17741841165.55 0.9997 0.9997 2026-06-12 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0.0369 2026-06-25 0.0370 2026-06-26 0.0370 2026-06-29 0.0370 2026-06-30 1.0000 2026-06-01 1.0000 2026-06-02 1.0000 2026-06-03 1.0000 2026-06-04 1.0000 2026-06-05 1.0000 2026-06-08 1.0000 2026-06-09 1.0000 2026-06-10 1.0000 2026-06-11 1.0000 2026-06-12 1.0000 2026-06-15 1.0000 2026-06-16 1.0000 2026-06-17 1.0000 2026-06-18 1.0000 2026-06-22 1.0000 2026-06-23 1.0000 2026-06-24 1.0000 2026-06-25 1.0000 2026-06-26 1.0000 2026-06-29 1.0000 2026-06-30 N N Class P C000248580 1.00 567974932.86 567961676.2200 1.0000 2026-06-01 1.0000 2026-06-02 1.0000 2026-06-03 1.0000 2026-06-04 1.0000 2026-06-05 1.0000 2026-06-08 1.0000 2026-06-09 1.0000 2026-06-10 1.0000 2026-06-11 1.0000 2026-06-12 1.0000 2026-06-15 1.0000 2026-06-16 1.0000 2026-06-17 1.0000 2026-06-18 1.0000 2026-06-22 1.0000 2026-06-23 1.0000 2026-06-24 1.0000 2026-06-25 1.0000 2026-06-26 1.0000 2026-06-29 1.0000 2026-06-30 8999781.08 5221480.83 2026-06-01 8534382.99 5415849.11 2026-06-02 4040918.81 4028490.99 2026-06-03 2424864.89 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Class T C000250059 5000000.00 9165967007.75 9165775817.5700 1.0000 2026-06-01 1.0000 2026-06-02 1.0000 2026-06-03 1.0000 2026-06-04 1.0000 2026-06-05 1.0000 2026-06-08 1.0000 2026-06-09 1.0000 2026-06-10 1.0000 2026-06-11 1.0000 2026-06-12 1.0000 2026-06-15 1.0000 2026-06-16 1.0000 2026-06-17 1.0000 2026-06-18 1.0000 2026-06-22 1.0000 2026-06-23 1.0000 2026-06-24 1.0000 2026-06-25 1.0000 2026-06-26 1.0000 2026-06-29 1.0000 2026-06-30 55813802.16 23362876.22 2026-06-01 29827486.47 33704033.67 2026-06-02 10300728.59 17034449.65 2026-06-03 2718945.77 51470782.40 2026-06-04 135731801.98 12757762.79 2026-06-05 6324533.22 15186748.52 2026-06-08 21266469.91 34407915.34 2026-06-09 25133926.64 13600599.57 2026-06-10 27219024.04 102691910.14 2026-06-11 24733686.60 19820623.21 2026-06-12 25329711.98 42287005.77 2026-06-15 20171224.07 44228139.25 2026-06-16 56425943.64 301085910.84 2026-06-17 47212944.62 170329531.22 2026-06-18 133139131.25 50974994.77 2026-06-22 166079478.87 35798919.63 2026-06-23 1033835.48 43570077.24 2026-06-24 4620472.07 20529642.95 2026-06-25 694527962.19 64369755.34 2026-06-26 26719431.48 31473025.22 2026-06-29 79247060.90 26854588.85 2026-06-30 1593577601.93 1155539292.59 0.0353 2026-06-01 0.0353 2026-06-02 0.0353 2026-06-03 0.0353 2026-06-04 0.0353 2026-06-05 0.0353 2026-06-08 0.0353 2026-06-09 0.0354 2026-06-10 0.0354 2026-06-11 0.0354 2026-06-12 0.0354 2026-06-15 0.0354 2026-06-16 0.0354 2026-06-17 0.0355 2026-06-18 0.0355 2026-06-22 0.0355 2026-06-23 0.0355 2026-06-24 0.0355 2026-06-25 0.0356 2026-06-26 0.0356 2026-06-29 0.0356 2026-06-30 Y 389919.00 Retail investor 0.0705 0.00 N 100 [percent symbol] US Treasury Master Fund 100 [percent symbol] US Treasury Master Fund 902656883 5299000M97HC3J8TJ387 0001403166 Investment Company Y 2026-07-01 2026-07-01 2026-07-01 N N N 0.0000 9761848928.01 9761848928.01 1.0000 N Y Y N The master-feeder funds are parties to a written daily liquidity agreement; consistent with SEC staff interpretative guidance, ownership interests in the master fund are categorized as a Daily Liquid Asset/Weekly Liquid Asset by the feeder funds. UBS Series Funds 2026-07-08 /s/Rose Ann Bubloski Rose Ann Bubloski Vice President