I asked "a friend":
• Meta (META) ~3.1 %
• Alphabet (GOOGL + GOOG) ~3.8 %
• Tesla (TSLA) ~1.6 %
So just under 9%. Significant, I suppose, for just 3 of 500 stocks.
EDIT: since "etc." was mentioned, I thought I'd toss in some of the other top stocks in the S&P500:
• Apple Inc. (AAPL) ~6.7 %
• Microsoft Corp. (MSFT). ~6.6 %
• NVIDIA Corp. (NVDA) ~6.0 %
Amazon.com Inc. (AMZN) ~3.8 %
Another 20% or so. So the above seven stocks comprise about 30% of the S&P500 (Apple, Microsoft and NVIDIA are the "Big 3" at about 20% when combined).