我研究了一下定投的收益。 假設每個月月底以當月最後一個交易日收市價投入$1,000來買SPY。 比如， 上個月最後一個交易日12月29， SPY 475.31， 買入 2.1 股； 11 月份最後一個交易日11月30， SPY 456.4， 買入 2.2 股， 等等。這樣下來， 等於一年投入$12，000， 隻買不賣， 一直拿到2023年底。
如果2000年買了， 到2023年底， 從$12，000 變成 $47,258(含dividend)；
如果2009年買的， 到2023年底， 從$12，000 卻變成 $69,364(含dividend)；
這24年累積下來， 從 $288，000投入變成 $986,000;
同樣的策略， 如果買QQQ， 收益是SPY 的兩倍，從$288，000 漲到 $2，000，000;
[Year Bought] [Amount（$)] [Hold to 2023 End] [Dividend] [Total]
2000 $12,000 $40,195.12 $7,063.64 $47,258.77
2001 $12,000 $48,230.56 $8,326.34 $56,556.90
2002 $12,000 $58,287.58 $9,882.88 $68,170.45
2003 $12,000 $59,146.74 $9,847.50 $68,994.25
2004 $12,000 $50,150.78 $8,158.72 $58,309.50
2005 $12,000 $47,210.84 $7,455.28 $54,666.12
2006 $12,000 $43,275.29 $6,629.02 $49,904.31
2007 $12,000 $38,610.55 $5,704.32 $44,314.86
2008 $12,000 $48,139.81 $6,818.39 $54,958.19
2009 $12,000 $61,016.96 $8,347.23 $69,364.19
2010 $12,000 $50,523.01 $6,676.67 $57,199.68
2011 $12,000 $44,599.56 $5,664.56 $50,264.12
2012 $12,000 $41,134.00 $4,991.40 $46,125.40
2013 $12,000 $34,645.77 $3,968.38 $38,614.15
2014 $12,000 $29,385.79 $3,144.65 $32,530.44
2015 $12,000 $27,820.05 $2,738.95 $30,559.00
2016 $12,000 $27,152.22 $2,427.74 $29,579.96
2017 $12,000 $23,207.69 $1,848.98 $25,056.67
2018 $12,000 $20,889.57 $1,444.43 $22,334.00
2019 $12,000 $19,495.49 $1,132.05 $20,627.54
2020 $12,000 $17,940.75 $827.67 $18,768.42
2021 $12,000 $13,437.43 $460.91 $13,898.34
2022 $12,000 $14,088.77 $299.78 $14,388.55
2023 $12,000 $13,265.95 $106.61 $13,372.56
Sum $288,000 $871,850 $113,966 $985,816
For QQQ:
Sum $288,000 $1,893,246.01 $81,654.47 $1,974,900.48
