Even the Americans sitting on piles of cash aren't using it correctly to build wealth

You should instead invest your excess savings in the stock market for the best returns, NerdWallet's retirement and investing specialist Arielle O'Shea recommends. The easiest way to put your savings to work is through a 401(k), which invests your money in stocks through low-cost index funds or exchange-traded funds. The average American is holding more than $32,000 in cash, a new study from NerdWallet found.