James Saft is a Reuters columnist. The opinions expressed are his own.

It has been a tough few weeks for momentum investors.

One time darlings like Amazon, Netflix and Green Mountain Coffee Roasters have taken serious tumbles, dealing losses.

Meanwhile, the financial industry, the sector which arguably hasn’t produced positive returns since the 1980s, are on a bit of a tear, bolstered by the latest European rescue and some reassuring U.S. economic data.

There are several intriguing reasons to believe that momentum investing has seen its best days. Momentum investing, beloved by day traders and some hedge funds, is the strategy of riding hot stocks higher while selling laggards.

While the tactic itself is probably as old as the stock market, momentum investing attracted increasing interest in the 1970s and 1980s, culminating in a number of academic studies, which seemed to show that it added value.

Those former go-go stocks are on the retreat for a variety of reasons.

Amazon warned Tuesday that it could slide into the red in the fourth quarter due to heavy spending on medium-term development projects. Amazon shares fell more than 10 percent that day. Even after a rally on Thursday, its stock remains more than 20 percent down from October peaks.