U.S. stocks gained steam Monday, as investors continued to digest comments on interest rates from Federal Reserve Chair Janet Yellen on Friday. Yellen said the case for a hike has 'strengthened in recent months.' Investors now await Friday's August jobs report. Mylan (MYL) - Get Report shares rose 1.8 percent after the company said it would start a generic version of the life-saving EpiPen. The company sparked a wave of controversy after raising the price of the drug last week by 400 percent. The generic version is said to be priced 50 percent less than the branded line. Herbalife (HLF) - Get Report rose 1.7 percent after billionaire activist Carl Icahn late Friday reported that he had acquired 2.3 million additional shares of the nutritional supplements company. Finally, personal income in the U.S. rose 0.4 percent in July, matching estimates. Consumer spending gained 0.3 percent, also in-line with estimates. TheStreet's Scott Gamm reports from Wall Street.