This year, saying “all-time highs” has started to sound like a broken record. Nothing has seemed to rattle the market much in 2021, with volatility at historic low levels. But after the summer lull, things to tend to get exciting again for investors in September in what is historically the worst-performing month of the year, with the FTSE 100 falling on average 1.2%. However, although the average return is bad for the month, about half of all Septembers have positive returns. The problem is that when the market does fall in this month, the falls can be very large.