The 500 largest non-financial companies in the U.S. hold $994 billion in cash and short-term investments, up about 8 percent from last year, according to an exclusive study conducted by The Wall Street Journal. Some of the largest tech companies like Google (GOOG) and Apple (AAPL) have tens of billions on their balance sheets.

There is nothing new about corporations holding high cash balances during a recession, since companies want to maintain a buffer against falling sales and earnings losses. But it raises the question of what will happen to the cash as the economy recovers.

There are a few possibilities:

1. The companies could simply hold the money and earn 1 percent on it. Apple in particular has signaled that it has no plans for its cash, and it rarely makes acquisitions. Apple generates more cash each quarter, but its board has no duty to do anything other than put the money in the bank, which does not do shareholders any favors.

2. Some firms will begin share buybacks. IBM (IBM) recently said it would increase its program by $5 billion. Some companies like McDonald's (MCD) have been aggressively buying their own shares for years. Fewer shares means better earnings per share (EPS). In theory, that should drive up a firm's share price.

3. Dividend hikes, particularly special dividends, have an immediate benefit for shareholders. Several years ago, Microsoft (MSFT) distributed billions of dollars of its cash balance to stockholders as a one-time event.

4. M&A activity is a use of cash that can cut two ways. The value of some buyout targets is still low because of the recession, which means that there are bargains. The tech sector, in particular, has been a hotbed of M&A. The flip side is that acquisitions often take up management's time and present integration challenges, so many buyouts end up dragging earnings down.

With nearly $1 trillion on big company balance sheets, one thing is certain: All that money is not going to just sit there unused.

Douglas A. McIntyre is an editor at 24/7 Wall St.