Earnings optimism supports pre-market gainsU.S. stock futures pointed to a firmer open on Tuesday as investors looked to recover from the previous session's decline, with upbeat corporate earnings encouraging buying across several sectors. Market sentiment improved after a series of better-than-expected quarterly reports, prompting traders to return to stocks following recent weakness. 3M, GM and Novartis lead pre-market moversAmong the early gainers, 3M (NYSE:MMM) advanced more than 7% in pre-market trading after reporting second-quarter earnings and revenue ahead of expectations while raising its full-year outlook. Technology stocks also provided support, with Nasdaq 100 futures rising approximately 1.2% ahead of the opening bell. 3M stock priceGeneral Motors stock priceNovartis stock priceAlphabet stock priceTesla stock price