Piggy banks

"Savers with uncertain life spans cannot stick to long-term investment plans when they invest directly in liquid assets. Before horizons are known, all savers will plan to roll over their short-term assets if returns turn out high. Ex post, the short-term investors will consume their liquid assets rather than reinvest them. Delegating investment decisions to an intermediary reduces the commitment problem, and leads to more efficient portfolios. The higher return to savings should also increase savings rates"--Federal Reserve Bank of New York web site.