40% of the S&P 500 value sits in just 10 stocks — and Bitcoin could feel the shock next

The S&P 500 has a concentration problem, and crypto still rides the same plumbing Ten companies have been carrying the S&P 500 like a heavy tool belt, and the weight shows up in one number: about 41% at the end of 2025. As of press time, the top ten add up to about 37.3%, and Nvidia alone accounts for about 7.37% of the index. That little drop matters as a signal worth tracking closely to determine whether it…