Key TakeawaysThe S&P 500 gained less than 0.1% on Friday, Jan. 12, 2024, as earnings season got underway with major banks releasing financial results.Airline stocks tumbled after Delta reduced its 2024 profit forecast and oil prices ticked higher.Bank of New York Mellon shares advanced as higher net interest revenue helped the financial firm beat analysts' expectations.U.S. equities were mixed as earnings season got underway with large U.S. banks reporting their financial results for the fourth quarter of 2 ...