BOSTON ( TheStreet) -- Spurred by a two-year bull market, investors poured $109 billion into mutual funds this year through April, including $28 billion into U.S. stock funds.Shares benefiting the most are last year's laggards, health-care companies, including UnitedHealth Group ( UNH) and Amerigroup ( AGP), which have outperformed the likes of Apple ( AAPL) and Intel ( INTC). UnitedHealth is up 40% this year, and Amerigroup 57%. The shift in sentiment among investors is startling, given equity funds had suffered outflows for two years, including $75 billion in 2010 alone. Investors are more confident as the economy has stabilized, the job market is growing and companies are reporting outsized profits. That's a dramatic change from two years ago, when falling stocks cut in half many Americans' 401(k) portfolios, unemployment was on its way to topping 10% and corporate losses piled up.