The biggest US banks stated that they would boost payouts to shareholders after the Federal Reserve affirmed they are healthy enough to use.Five of the six biggest banks elevated their dividends on Monday increasing the per-share payouts 40% from levels they held steady or cut during the coronavirus-induced economic collapse. They also committed to buying tens of billions of dollars of their own stock.Morgan Stanley led the way, doubling its quarterly dividend to 70 cents a share and revealing plans to buy back up to $12 billion of its stock in the next 12 months. Morgan Stanley shares leaped 2.6% in after-hours trading.Citigroup Inc. was the lone megabank not to raise its dividend, keeping it unchanged at 51 cents but leaving the door open for an increase. It didn’t announce a new buyback plan. Its stock, already trailing the other large bank increases this year, dropped after hours by almost 1%.