Wall Street experienced its most significant decline in 19 months, primarily driven by disappointing quarterly results from tech giants Tesla and Alphabet. Tesla's shares plummeted by 11.2%, marking a potential loss of over $83 billion in market value due to the lowest profit margins reported in over five years and missing earnings estimates. Alphabet, despite beating second-quarter earnings expectations, saw a 4.1% drop as investors reacted to slowing advertising growth and high capital expenses. This downturn raised concerns about the sustainability of the recent tech rally, particularly for the 'Magnificent Seven' tech stocks that have seen substantial gains this year. Analysts cautioned that if significant capital exits the tech sector, it could lead to broader market declines, impacting other large-cap tech stocks like Nvidia and Microsoft. Despite these challenges, the overall earnings season has seen about 80% of S&P 500 companies exceeding expectations, keeping some optimism alive amid economic uncertainties.