Several of the biggest AI-related stocks have fallen hard from their recent highs. Google: down 30% from its highs. Nvidia & Broadcom: down 25%. Meta: down 20%. The most common explanation is that heavy AI spending has investors questioning whether the payoff will justify the cost. And because these companies make up such a large slice of the S&P 500, "concentration risk" is back in the headlines. So, what would a 50% drop in these stocks actually do to a diversified portfolio? In today's...