The annual study published by financial research firm Dalbar reports that the average investor in U.S. stock mutual funds earned 7.3% last year versus the S&P 500’s 12% return. This according to last week’s Wall Street Journal.

While the study showed the spread has improved from both the past three and five years (when underperformance reached 5.5 and 4.8 percentage points, respectively), the article explains how investors are “already at a disadvantage” due to the underperformance of actively managed funds–to the tune of 19%. This according to data provided by Bank of America Merrill Lynch.

The article points out that investors’ propensity to bail during market dips—consequently buying high and selling low—only exacerbates the underperformance. Investors, it argues, “buy and sell along the way depending on market conditions or even life events” rather than in linear fashion.

While Dalbar has been criticized, the article says, for “overstating how much investors lag the market,” the firm’s basic findings are supported by other studies. “It is every investor’s dream,” according to WSJ, “to get out before a market tumble slices their portfolio, but episodes like last week’s tumble show that trying to do so is like death by a thousand cuts.”