Shareholders are starting to push back against outsize CEO pay, but some of the nation's best-known companies are still overpaying their chief executives for paltry performance.

That's according to investor advocacy group As You Sow, which published its eighth-annual report Thursday on the 100 most overpaid bosses of S&P 500 companies. Based on data provided by Institutional Shareholder Services, a shareholder advisory firm, the report found that CEO pay is increasingly becoming untethered from company performance, and, as a result, shareholders are increasingly rejecting pay packages when put to a vote. READ MORE