Today's gain of 2.2% for the S&P 500 was the second best start to August over the last 50 years. The first day of August 1984 is the only day that saw a bigger gain at 2.27%. Below is a table showing the best starts to August since 1960. After the 2.27% gain on the first trading day of August in 1984, the S&P 500 went on to gain another 8.18% during the rest of the month. The index has goner higher during the rest of the month following all gains of 1% or more on the first day of August.