Stock market today: S&P 500, Nasdaq rise as tech leads, UnitedHealth weighs on Dow amid earnings flood

Group 1 - US stocks experienced a rise on Tuesday, driven by optimism in the tech sector, despite political concerns and a decline in UnitedHealth's stock [1][2] - The Nasdaq Composite led the gains with an increase of 0.6%, while the S&P 500 rose by 0.3%, and the Dow Jones Industrial Average fell by 0.8% due to UnitedHealth's significant drop [1][2] - UnitedHealth's shares fell over 15% after a quarterly profit beat, as the Trump administration's Medicare payment rate proposal did not meet Wall Street's expectations [2] Group 2 - General Motors reported a fourth-quarter earnings beat, raised its dividend, and announced a $6 billion share buyback plan [4] - The S&P 500 is approaching record highs, buoyed by positive news from memory chipmakers ahead of major earnings reports from key tech companies [3] - The Federal Reserve began a two-day meeting, with expectations to maintain the benchmark interest rate, while markets are looking for indications on future rate cuts [4]