Uncertainty about the economy has led companies to continue building their cash reserves instead of making capital investments or hiring new workers, CNBC reports. JPMorgan says the cash holdings of companies in the S&P 500 are approaching $1.5 trillion.

While the buildup of cash has been going on for years now, Jim Paulsen, Wells Capital Management chief strategist, argues that investors are going to start losing patience with companies given the stock market's poor performance recently. He suggests activist investors may begin focusing on companies' cash holdings.

The November elections and the fiscal cliff are other issues causing companies to behave cautiously. Quincy Krosby, chief market strategist at Prudential Annuities, says companies may pay out special dividends later this year because of tax considerations.