Weighted stocks explode causing a divergence in the century! UnitedHealth Group Incorporated (UNH.US) plunged 22% in a single day dragging down the Dow Jones Industrial Average.

On Thursday, the Dow fell by 1.2%, while the S&P 500 index rose by as much as 0.6% at the same time. This situation is extremely rare - the "culprit" of this historic deviation is the stock price plummet of the healthcare giant UnitedHealth Group Incorporated (UNH.US). As the most weighted component in the Dow Jones Index, UnitedHealth Group Incorporated saw its stock price drop by 18% after releasing earnings below expectations (for the first time in over a decade) and lowering its full-year performance forecast, marking the largest single-day drop since 1999. By the close of the US stock market on Thursday, UnitedHealth Group Incorporated had fallen by 22.38%, to $454.11. Data compiled by the media shows that the Dow fell by 1% or more while the S&P 500 rose by at least 0.5%, a situation that has only occurred once since 1954. JonesTrading's Chief Market Strategist Michael O'Rourke said, "While major stock indices usually move in sync, today's movements reflect a rare, significant volatility in a high-priced stock in the Dow Jones Industrial Average, causing a market divergence." A key difference between the Dow Jones Index and the broader S&P 500 index is the weighting method of their component stocks. The Dow Jones Index uses price weighting, meaning that the price changes of high-priced stocks have a greater impact on the index level than the price changes of low-priced stocks. The S&P 500 index uses market capitalization weighting. UnitedHealth Group Incorporated, the health insurance company with the highest weighting in the Dow Jones Index, reported first-quarter profits below analyst expectations, marking its largest drop since 1999. The company also lowered its profit forecast for the year. For UnitedHealth Group Incorporated, this downward revision of profit expectations is rare, as the company usually offers conservative forecasts and typically raises profit expectations over time. UnitedHealth Group Incorporated lowered its annual profit forecast due to expected cost increases. The company currently expects earnings per share (EPS) for the year to be between $26 and $26.5, considerably lower than the previous estimate of $29.50 to $30 and below the market expectation of $29.74. Historic deviation between the Dow Jones Index and the S&P 500 Index This will be quite a significant shift for the Dow Jones Index, which has outperformed the other two major indices in this year's market turmoil. As of Wednesday's close, the Dow Jones Index had fallen by 6.8% this year, while the S&P 500 index had fallen by 10%, and the tech-heavy Nasdaq 100 index had fallen by 13%. In the ranking of the Dow Jones Index, following UnitedHealth Group Incorporated are Goldman Sachs Group, Inc. (GS.US), Microsoft Corporation (MSFT.US), and Home Depot, Inc. (HD.US), while the top positions in the S&P 500 Index are held by tech giants Apple Inc. (AAPL.US), Microsoft Corporation, NVIDIA Corporation (NVDA.US), Amazon.com, Inc. (AMZN.US), and Meta Platforms (META.US). Meanwhile, as traders carefully study the latest batch of earnings reports and try to evaluate the impact of President Trump's tariff offensive, the market has seen a slight increase.