While we’re now more than two years into the bull market, lower-quality stocks are ccontinuing to lead the market’s rise — bucking the usual trend seen in bull markets, MarketWatch’s Mark Hulbert says.

In his latest column, Hulbert says that it was to be expected that “junk”-type stocks rose the most in the early stages of the bull run, since they were hit hardest during the preceding bear market. But, Hulbert says, “Had this bull market conformed to the historical pattern, then we would have expected that this junk-over-quality pattern would have lasted only a matter of months following the end of the bear market in March 2009. … But once that snap-back rally — some might say “dead cat bounce” — had played itself out, market leadership should have begun to shift to higher-quality companies. Historical precedent suggested that this transition should have begun at least by the time the bull market was one year old.”

The reason the transition hasn’t occurred, Hulbert says, may be one that top value investor Jeremy Grantham has cited: the Federal Reserve and government’s massive stimulus policies have subsidized risk-taking, which has pushed investors into riskier stocks.

“Indeed, according to Grantham, he is hard pressed to find other times in U.S. stock market history when quality (large-cap value) has been as undervalued as it is today, relative to junk (small-cap growth),” Hulbert writes.

Hulbert and Grantham think there will be a transition to higher-quality at some point, but no one knows for sure when that will happen. It depends on many factors, Hulbert writes — including whether the Federal Reserve employs a third round of quantitative easing.