If you invested in the stock market this year, chances are you came out pretty well. The S&P 500 and Nasdaq composite index rose to record highs, as investor enthusiasm for artificial intelligence fueled a massive bull run, and investors cheered the Federal Reserve’s shift to lower interest rates. Participants in 401(k) and 403(b) plans also benefited big, with Fidelity Investments reporting that account balances reached their highest averages on record.Subscribe to The Post Most newsletter for