Investors could be disappointed if they anticipate tons of money waiting to get back into the stock market, since cash on the sidelines is much less than estimated, Goldman Sachs analysts said.

Based on their calculations, net equity inflow from individuals, institutional investors and corporations over the next several quarters could total $600 billion, the analysts said in a research note on Wednesday.

'Cash on the sidelines' is much less than the $3.4 trillion in money market mutual fund assets that market participants typically cite as the No. 1 reason stocks are poised to rally, analysts wrote.

Investors have been keeping cash in money market mutual funds, which are considered a safe haven compared with equities.

Cash on the sidelines is often cited as a likely reason why stocks stand to gain more. The Standard & Poor's 500 <.SPX> index is already up some 55 percent since its early March low.

The potential inflow of $600 billion over a 12-month period could be a bullish backdrop for investors but will not be sufficient to sustain a robust market rally without accompanying improvements in the U.S. economy and the corporate earnings outlook, the analysts wrote.