Multi-asset portfolio managers are facing a tough spot right now. Keeping pace with the S&P 500's concentration isn't just hard—it's becoming a structural challenge. When market leadership narrows dramatically, diversified portfolios naturally lag, and that's exactly the environment we're in. The real issue? Concentration risk. A few mega-cap names are driving most of the index's gains, making it increasingly difficult for traditional asset allocators to match returns without taking on outsized exposure to a handful of stocks. It's a reminder that chasing index returns in concentrated markets forces investors into uncomfortable positions.