As stocks soar, talk of a bubble is making a comeback on Wall Street. Should investors be worried? - MarketWatch
1. S&P 500 up nearly 30% since April amid bubble concerns. 2. Top stocks represent 40% of S&P 500 value, showcasing concentration risk. 3. Speculative trading activity rising with retail pushing market volatility. 4. Expectations of potential tariffs could revive inflation and weaken growth. 5. AI and tech valuations stir debate over bubble risks, reminiscent of past market crashes.