The U.S. stock market is experiencing a significant rally, but experts warn of increasing vulnerability. The technology sector, which now represents approximately 35% of the S&P 500's market capitalization, is particularly under scrutiny. Analysts from Societe Generale have cautioned investors to remain vigilant for a potential bubble burst. Additionally, Warren Buffett's preferred valuation metric is signaling concerns about the market's safety. A billionaire investor has also issued a stark warning regarding the future trajectory of the stock market, highlighting the risks associated with new technology and substantial investments that may lead to inflated valuations and subsequent market corrections.