Most would agree that valuations in the current mature bull market make buying equities a bit less alluring than they were, say, when the U.S. was emerging from the 2008 global financial crisis. However, according to a MarketWatch article by Mark Hulbert, an indicator referred to as the Coppock Guide is suggesting that the potential still exists for “significant returns.”

Edwin Coppock was a technical analyst who proposed his market-timing model in an article for Barron’s in 1962. Hulbert explains it as a “momentum indicator that filters out shorter-term market swings to focus on the market’s long-term trend.” He says the calculation (which involves a number of steps using average percentage changes in the market over different periods) generated a ‘buy’ signal at the end of this past July, the first time it has done so since May of 2009.

According to James Stack, an investment adviser and editor of InvesTech Research, the Coppock Guide has generated 12 other similar signals since 1962 and that the overwhelming majority were a success. And, although Stack predicts that this bull market will peak sometime in 2017, Hulbert says he is currently recommending that “clients allocate 81% of their investment portfolios to the stock market.”

Hulbert doesn’t necessarily take the position that a robust bull market is in the offing, but suggests that we “think twice before becoming too confident that the only realistic and reasonable thing for the stock market is to produce, at best, mediocre returns in the years ahead.”