With a bull market raging for stocks, many investors are wondering which indicator will tell them when it’s time to get out.

The widely followed 200-day moving average isn’t the one, says MarketWatch columnist Mark Hulbert. Market participants who use the indicator view a drop below that average as a signal that the bull market is over.

“This indicator leaves a lot to be desired,” Hulbert writes.

Forbes Columnist: ‘Who the Hell Cleared This?’

He looked at the index going back to the 19^th century, creating a portfolio that was fully invested in the Dow Jones Industrial Average whenever the gauge was above its 200-day moving average, and completely out of the market whenever the index was below the average.

Since 1950, the moving-average portfolio produced an annualized return of 6.4 percent, excluding dividends and trading fees, underperforming the 7 percent return for a buy-and-hold portfolio.

Since 1990, the discrepancy has been even greater, with a 3.8 percent annualized return for the moving-average portfolio, compared with 7.3 percent for buying and holding.

“The picture that emerges is of an indicator whose best years came in the early part of the last century,” he writes. “Its market timing value has gotten progressively worse in recent decades.”

Relying on any single indicator to tell you when a market move is coming seems foolhardy, and the 200-day moving average serves as a good example.

“The bottom line: If the 200-day moving average is the best we can do in our search for our top-identifying indicators, the rational thing to do would probably be to give up and resign ourselves to buying and holding,” Hulbert writes. “Let’s hope there’s something better.”

Many experts think stocks are capable of climbing more mountains, especially now that retail investors are enthusiastic.

“With individual investors’ allocation to stocks at 30-year lows, and stocks having been liquidated in favor of bonds for the last five years, there could be a long runway for money to return to stocks and drive prices higher,” Darell Krasnoff, managing director at Bel Air Investment Advisors, tells The Wall Street Journal.

Forbes Columnist: ‘Who the Hell Cleared This?’