Investing.com - JPMorgan Chase (NYSE:JPM) says first-quarter earnings will be better than expected, driven by more than the benefit of lower corporate taxes.In a note to clients, the Wall Street firm said it expects earnings to rise by 21%, well above the consensus forecast of 17.5%.JPMorgan says earnings will be lifted by a host of economic factors, including rising disposable income and consumer confidence.The firm says strong corporate profits and record share buybacks will drive stock prices higher, after a unusually volatile period in which the market suffered two corrections in a little more than a month.Earnings rose just under 15% in the fourth quarter and are forecast to grow by 18.5% for all of 2018.