Last year's star stocks fade out

— -- Following the leaders has become a loser's game on Wall Street.

Stocks that were stars coming into the year are some of the worst performers in a market that's struggling through another tumultuous period. And it's unclear what groups might emerge to lead the market out of its funk.

Worse yet, "It doesn't seem like anything is taking a leadership position," says Jack Ablin of Harris Private Bank. "There are no places to hide."

Even winners from earlier in the year are rolling over, says Justin Walters, co-founder of Bespoke Investment Group. The top-performing large stocks in the first half of the year are down 25.7% in the second half, he says.

There are several reasons why so many former leaders are hurting:

•The unwinding of the global commodity boom. With global growth in question, makers of commodities, industrial equipment and energy are getting hammered, says Michael Farr of Farr Miller & Washington. If the world economy slows, demand for raw materials will, too.

•Tech sag. Many tech darlings have flamed out as investors worry about where the sector will grow.