N-MFP2 0000798244 XXXXXXXX 2019-03-31 0000798244 CQT3VZHUKW04X1YLM325 S000000762 12 N N 033-07638 Massachusetts Financial Services Company 801-17352 Deloitte & Touche LLP Boston MA Massachusetts Financial Services Company MFS Service Center, Inc 0000769188 084-01316 N N N Exempt Government N 19 19 44575822.18 31492613.05 30405917.58 35001071.44 39061668.62 214372102.72 214570853.08 217882770.75 217374368.31 203044793.77 0.2017 0.1432 0.1395 0.1610 0.1807 0.9698 0.9759 0.9997 0.9997 0.9394 0.00 216114092.24 216115860.85 31428.08 1138621.76 215008667.17 215238674.0790 1.0000 0.0242 0.9990 0.9989 0.9989 0.9989 0.9989 C000002179 1000.00 99804913.01 99911061.6850 0.9990 0.9989 0.9989 0.9989 0.9989 658091.47 1113430.27 119294.36 871823.52 152435.07 506850.21 859625.85 758035.03 459190.07 740957.08 1801900.83 3181409.86 0.0171 Y For Class A during the period, MFS waived: $846 management fees; MFD waived: $21,282 12b-1 fees. C000002180 250.00 252878.18 253147.1470 0.9990 0.9990 0.9989 0.9989 0.9989 503.55 0.00 4955.00 0.00 0.00 4900.00 14138.58 4652.35 200.00 926.00 19790.13 10478.35 0.0166 Y For Class 529B during the period, MFS waived: $2 management fees; MFD waived: $211 12b-1 fees. C000002181 250.00 6878451.15 6885743.3060 0.9990 0.9989 0.9989 0.9989 0.9989 68516.26 3857.11 28107.07 22850.03 42803.08 26692.79 14044.00 50387.18 38678.29 35934.62 149265.44 135864.62 0.0166 Y For Class 529C during the period, MFS waived: $58 management fees; MFD waived: $5,855 12b-1 fees. C000002182 1000.00 10145162.93 10155958.7460 0.9989 0.9989 0.9989 0.9989 0.9989 106548.18 167040.78 64504.09 233922.04 85040.01 112457.21 29206.61 280231.31 43287.48 77410.06 236390.72 713012.59 0.0171 Y For Class B during the period, MFS waived: $88 management fees; MFD waived: $8,802 12b-1 fees. C000002183 1000.00 19221666.88 19242624.3910 0.9989 0.9989 0.9989 0.9989 0.9989 100263.30 421116.67 549931.35 340950.72 312143.24 344841.82 156745.84 706970.53 57534.09 596522.44 1094368.63 2054671.97 0.0171 Y For Class C during the period, MFS waived: $169 management fees; MFD waived: $16,981 12b-1 fees. C000002184 1.00 8059278.48 8067834.0480 0.9989 0.9989 0.9989 0.9989 0.9989 19364.35 236291.37 16786.89 49176.94 7054.15 52742.49 16636.03 8912.99 5479.42 13175.19 55357.18 124077.45 0.0171 Y For Class R1 during the period, MFS waived: $68 management fees; MFD waived: $6,864 12b-1 fees. C000002186 1.00 33027634.63 33063577.6670 0.9989 0.9989 0.9989 0.9989 0.9989 89252.64 342915.57 10787.04 132463.92 68648.39 293576.29 59664.15 157285.09 8286.74 871036.82 190275.57 1744521.41 0.0171 Y For Class R2 during the period, MFS waived: $287 management fees; MFD waived: $14,416 12b-1 fees. C000002187 1.00 16414104.84 16431664.9430 0.9990 0.9990 0.9989 0.9989 0.9989 1801640.22 368360.15 5835.94 320693.55 41662.42 1379354.19 48796.50 33032.90 9503.89 152666.54 1511176.39 1885747.18 0.0171 Y For Class R3 during the period, MFS waived: $144 management fees; MFD waived: $3,628 12b-1 fees. C000002188 1.00 2755936.17 2758859.7100 0.9990 0.9989 0.9989 0.9989 0.9989 3746.33 780.57 0.00 0.00 0.00 0.00 4875.68 0.00 179.99 827.21 8647.22 827.21 0.0171 Y For Class R4 during the period, MFS waived: $23 management fees. C000002189 250.00 18323034.76 18342463.0860 0.9990 0.9990 0.9990 0.9989 0.9989 362801.21 26777.07 188224.38 147101.21 191832.94 60787.25 174495.87 114416.37 50224.06 45995.66 630649.18 371327.94 0.0166 Y For Class 529A during the period, MFS waived: $154 management fees; MFD waived: $3,870 12b-1 fees. C000206004 1.00 50314.07 50367.4300 0.9990 0.9989 0.9989 0.9989 0.9989 67.83 0.00 0.00 0.00 0.00 0.00 3.03 0.00 0.00 0.00 66.98 0.00 0.0178 N C000206005 1.00 75292.07 75371.9200 0.9990 0.9989 0.9989 0.9989 0.9989 86.05 0.00 0.00 0.00 0.00 0.00 4.58 0.00 0.00 0.00 84.80 0.00 0.0171 Y For Class I during the period, MFS waived: $1 management fees. Federal Farm Credit Bank Federal Farm Credit Bank 313312EC0 US313312EC02 U.S. Government Agency Debt Y 2019-04-09 2019-04-09 2019-04-09 N N N 0.0245 25636205.94 25636205.94 0.1192 N N Y N Federal Farm Credit Bank Federal Farm Credit Bank 313312ED8 US313312ED84 U.S. Government Agency Debt Y 2019-04-10 2019-04-10 2019-04-10 N N N 0.0246 6596007.00 6596007.00 0.0307 N N Y N Federal Farm Credit Bank Federal Farm Credit Bank 313312EK2 US313312EK28 U.S. Government Agency Debt Y 2019-04-16 2019-04-16 2019-04-16 N N N 0.0246 11546345.72 11546345.72 0.0537 N N Y N Federal Home Loan Bank Federal Home Loan Bank 313384DX4 2549001DPIFGXC1TOL40 US313384DX43 U.S. Government Agency Debt Y 2019-04-04 2019-04-04 2019-04-04 N N N 0.0245 6527683.30 6527683.30 0.0304 N N Y N Federal Home Loan Bank Federal Home Loan Bank 313384EE5 2549001DPIFGXC1TOL40 US313384EE52 U.S. Government Agency Debt Y 2019-04-11 2019-04-11 2019-04-11 N N N 0.0246 6995294.46 6995294.46 0.0325 N N Y N Federal Home Loan Bank Federal Home Loan Bank 313384EF2 2549001DPIFGXC1TOL40 US313384EF28 U.S. Government Agency Debt Y 2019-04-12 2019-04-12 2019-04-12 N N N 0.0246 7994084.48 7994084.48 0.0372 N N Y N Federal Home Loan Bank Federal Home Loan Bank 313384EJ4 2549001DPIFGXC1TOL40 US313384EJ40 U.S. Government Agency Debt Y 2019-04-15 2019-04-15 2019-04-15 N N N 0.0246 8791718.23 8791718.23 0.0409 N N Y N Federal Home Loan Bank Federal Home Loan Bank 313384EL9 2549001DPIFGXC1TOL40 US313384EL95 U.S. Government Agency Debt Y 2019-04-17 2019-04-17 2019-04-17 N N N 0.0246 4195482.65 4195482.65 0.0195 N N Y N Federal Home Loan Bank Federal Home Loan Bank 313384ES4 2549001DPIFGXC1TOL40 US313384ES49 U.S. Government Agency Debt Y 2019-04-23 2019-04-23 2019-04-23 N N N 0.0246 8886837.88 8886837.88 0.0413 N N Y N Federal Home Loan Bank Federal Home Loan Bank 313384GP8 2549001DPIFGXC1TOL40 US313384GP81 U.S. Government Agency Debt Y 2019-06-07 2019-06-07 2019-06-07 N N N 0.0246 4380182.88 4380182.88 0.0204 N N N N Federal Home Loan Bank Federal Home Loan Bank 313384HY8 US313384HY89 U.S. Government Agency Debt Y 2019-07-10 2019-07-10 2019-07-10 N N N 0.0247 8691180.58 8691180.58 0.0404 N N N N Federal Home Loan Mortgage Corp. Federal Home Loan Mortgage Corp. 313396DW0 S6XOOCT0IEG5ABCC6L87 US313396DW08 U.S. Government Agency Debt Y 2019-04-03 2019-04-03 2019-04-03 N N N 0.0245 9198763.15 9198763.15 0.0428 N N Y N Federal Home Loan Mortgage Corp. Federal Home Loan Mortgage Corp. 313396DX8 S6XOOCT0IEG5ABCC6L87 US313396DX80 U.S. Government Agency Debt Y 2019-04-04 2019-04-04 2019-04-04 N N N 0.0245 9198144.64 9198144.64 0.0428 N N Y N Federal Home Loan Mortgage Corp. Federal Home Loan Mortgage Corp. 313396EL3 S6XOOCT0IEG5ABCC6L87 US313396EL34 U.S. Government Agency Debt Y 2019-04-17 2019-04-17 2019-04-17 N N N 0.0246 10633550.67 10633550.67 0.0495 N N Y N Federal Home Loan Mortgage Corp. Federal Home Loan Mortgage Corp. 313396ET6 S6XOOCT0IEG5ABCC6L87 US313396ET69 U.S. Government Agency Debt Y 2019-04-24 2019-04-24 2019-04-24 N N N 0.0246 3494588.62 3494588.62 0.0163 N N Y N Federal Home Loan Mortgage Corp. Federal Home Loan Mortgage Corp. 313396FG3 S6XOOCT0IEG5ABCC6L87 US313396FG30 U.S. Government Agency Debt Y 2019-05-07 2019-05-07 2019-05-07 N N N 0.0246 5123570.88 5123570.88 0.0238 N N Y N Federal Home Loan Mortgage Corp. Federal Home Loan Mortgage Corp. 313396FN8 S6XOOCT0IEG5ABCC6L87 US313396FN80 U.S. Government Agency Debt Y 2019-05-13 2019-05-13 2019-05-13 N N N 0.0246 5285036.35 5285036.35 0.0246 N N Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588DU6 B1V7KEBTPIMZEU4LTD58 US313588DU65 U.S. Government Agency Debt Y 2019-04-01 2019-04-01 2019-04-01 N N N 0.0001 9471000.00 9471000.00 0.0440 N Y Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588EB7 B1V7KEBTPIMZEU4LTD58 US313588EB75 U.S. Government Agency Debt Y 2019-04-08 2019-04-08 2019-04-08 N N N 0.0245 5997176.64 5997176.64 0.0279 N N Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588EJ0 B1V7KEBTPIMZEU4LTD58 US313588EJ02 U.S. Government Agency Debt Y 2019-04-15 2019-04-15 2019-04-15 N N N 0.0246 2997176.67 2997176.67 0.0139 N N Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588EL5 B1V7KEBTPIMZEU4LTD58 US313588EL57 U.S. Government Agency Debt Y 2019-04-17 2019-04-17 2019-04-17 N N N 0.0246 499462.22 499462.22 0.0023 N N Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588EM3 B1V7KEBTPIMZEU4LTD58 US313588EM31 U.S. Government Agency Debt Y 2019-04-18 2019-04-18 2019-04-18 N N N 0.0246 8839886.40 8839886.40 0.0411 N N Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588ER2 B1V7KEBTPIMZEU4LTD58 US313588ER28 U.S. Government Agency Debt Y 2019-04-22 2019-04-22 2019-04-22 N N N 0.0246 4393788.65 4393788.65 0.0204 N N Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588EU5 B1V7KEBTPIMZEU4LTD58 US313588EU56 U.S. Government Agency Debt Y 2019-04-25 2019-04-25 2019-04-25 N N N 0.0246 7456950.04 7456950.04 0.0347 N N Y N Federal National Mortgage Assoc. Federal National Mortgage Assoc. 313588EY7 B1V7KEBTPIMZEU4LTD58 US313588EY78 U.S. Government Agency Debt Y 2019-04-29 2019-04-29 2019-04-29 N N N 0.0246 3693035.79 3693035.79 0.0172 N N Y N JPMorgan Chase Jp Morgan Tri Party Repo 2.500000% 8I5DZWZKVSZI1NUHU748 0001168163 446199002_2.50_0401 U.S. Treasury Repurchase Agreement, if collateralized only by U.S. Treasuries (including Strips) and cash Y N U.S. Treasury Bill 254900HROIFWPRGM1V77 2019-09-26 2.360000 100.00 98.82 U.S. Treasuries (including strips) U.S. Treasury Bill 254900HROIFWPRGM1V77 2019-12-31 1.875000 950700.00 951051.77 U.S. Treasuries (including strips) U.S. Treasury Bill 254900HROIFWPRGM1V77 2021-01-15 2.000000 2881400.00 2876905.45 U.S. Treasuries (including strips) U.S. Treasury Bill 254900HROIFWPRGM1V77 2019-09-30 1.000000 1342500.00 1339416.35 U.S. Treasuries (including strips) Y 2019-04-01 2019-04-01 2019-04-01 N N N 0.0250 5065000.00 5065000.00 0.0236 N Y Y N U.S. Treasury Bill U.S. Treasury Bill 912796RP6 254900HROIFWPRGM1V77 US912796RP63 U.S. Treasury Debt Y 2019-05-09 2019-05-09 2019-05-09 N N N 0.0240 99750.36 99750.36 0.0005 N Y Y N U.S. Treasury Bill U.S. Treasury Bill 912796RQ4 254900HROIFWPRGM1V77 US912796RQ47 U.S. Treasury Debt Y 2019-05-16 2019-05-16 2019-05-16 N N N 0.0240 1844536.34 1844536.34 0.0086 N Y Y N U.S. Treasury Bill U.S. Treasury Bill 912796UV9 254900HROIFWPRGM1V77 US912796UV94 U.S. Treasury Debt Y 2019-04-02 2019-04-02 2019-04-02 N N N 0.0241 9099400.31 9099400.31 0.0423 N Y Y N U.S. Treasury Bill U.S. Treasury Bill 912796UX5 254900HROIFWPRGM1V77 US912796UX50 U.S. Treasury Debt Y 2019-04-16 2019-04-16 2019-04-16 N N N 0.0240 8791319.15 8791319.15 0.0409 N Y Y N U.S. Treasury Bill U.S. Treasury Bill 912796UZ0 254900HROIFWPRGM1V77 US912796UZ09 U.S. Treasury Debt Y 2019-04-30 2019-04-30 2019-04-30 N N N 0.0243 4690932.24 4690932.24 0.0218 N Y Y N MFS Series Trust I 2019-04-05 /s/Kino Clark Kino Clark Assistant Treasurer