At a time when the general environment seems to be full of crises, the U.S. stock market is approaching its historical high. This paradox plagues everyone, including some of the largest asset managers. < / P > < p > Top Hedge Fund and public fund managers said looming threats, such as uncertainty over the reopening of schools, the November US election, tensions in international relations and the impact of monetary policy on inflation, could end the historic rally in the US stock market. < / P > < p > although the S & P 500 has risen more than 50% from its march low, the unemployment rate is still at double-digit percentages, and the federal government is still struggling to contain the new epidemic. The index’s price earnings ratio has risen to 26 times, well above the average of 18 times in the past decade. Because of this, some market insiders are cautious about asserting a market rebound. < / P > < p > “there’s a huge disconnect between fundamentals and the market,” says Brian Payne, investment officer at the Illinois teacher retirement fund. “There is too much money chasing investment, and the Federal Reserve is releasing water into the market, and these leverage funds cannot enter the real economy. As the election approaches, there are growing concerns about a big win, which could be the turning point for bullish sentiment to bearish sentiment. ” < / P > < p > the multi billion dollar hedge funds managed by Chris Rokos are warm and bullish in the short term, but are expected to be volatile later, as markets underestimate the possibility of greater volatility in the coming months. < / P > < p > to be sure, there have been gloomy predictions for months. In an webcast at the New York Economic Club on May 12, Stan Druckenmiller said the stock market risk return was at the worst level of his career. Since then, the S & P 500 has risen 18%, and Druckenmiller later said he was “too cautious.”. < / P > < p > despite the skepticism expressed by many investors, professional fund managers generally show the opposite style. The speed of the stock market rally has made the risk of missed opportunities particularly significant this year, forcing fund managers to reduce their cash holdings and move their stock positions to the most bullish level in history. However, there are still some well-known asset management institutions ringing the alarm. Brevan Howard asset management, a UK hedge fund, said in a client report this month that the impact of distance education in schools on working parents “may cause the labor market to suffer the same damage as a small and medium-sized economic recession” because they may be forced to shorten their working hours or resign. < / P > < p > “investors need to add schools to the commonly used economic indicators dashboard,” says brevan Howard. “The situation in education may be as important as other indicators.” < / P > < p > there is also the impact of vaccine competition. Roger Aliaga Diaz, chief economist for the Americas at Pioneer group, said it might take longer than expected to develop a reliable vaccine, or some people would resist it. < / P > < p > the market expects that R & D will be successful by the end of the year, “but production and distribution time may be much later than people think,” he said. “That would be a negative accident.” < p > < p > the strong returns of a few Mega cap stocks, such as apple, Microsoft and Amazon, have accounted for the majority of the S & P 500’s gains this year. These tech giants are on a strong rise because home ownership has made consumers more dependent on mobile devices and delivery services than ever before. Apple’s market value reached a record high of $2 trillion on Wednesday, becoming the first company in the United States to reach that level. However, international trade tensions, antitrust investigations, and the possibility of strengthening regulation if one comes to power may trigger a sharp fall in technology stocks.