The Dollar-Cost Discipline

Dollar-cost averaging — buying a fixed dollar amount on a fixed schedule regardless of price — defeats the single greatest enemy of the investor: thy own emotion.

Trying to time the market requires being right twice: when to sell and when to re-enter. The data is overwhelming: almost no one does this consistently. Even the professionals lose to a simple monthly contribution into a broad index.

DCA is not optimal in a strictly mathematical sense — lump-sum investing wins about 2/3 of the time historically. But DCA is optimal in the BEHAVIORAL sense, because it is a system thou wilt actually execute.