Industrial conglomerate 3M Company (NYSE: MMM) has outperformed the S&P 500 for the vast majority of the past two decades. It's a potential turning point for investors who must decide whether 3M's best days are gone or if the past several years are a temporary bump in a multidecade story of success. Your mind often gives more weight to recent events, which could help explain why Wall Street is down so much on 3M stock.