Storage and memory products makers dominated the index's top performers this year.The S&P 500 (^GSPC +0.32%) is on course for a solid 2025. With just a couple of trading days left in the year, the index is up almost 17%. That's not bad considering the average annual total return for the S&P 500 (including dividends) is about 10%.But five components in the large-cap index have blown that average away, posting gains of more than 200%.  The top fiveThe top S&P 500 performer for 2025 is Sandisk (SNDK +2.09%). T ...