Shares of Clear Channel Communications ( CCU - Get Report) were on the fritz Tuesday after a management shakeup at its radio group.

Late Monday, Clear Channel said that the CEO of its radio division, Randy Michaels, would take over its new technologies unit. The company did not announce a replacement for Michaels. The sudden redeployment was apparently worrisome to investors, and Clear Channel fell $4.94, or 16.5%, to $25 Tuesday. Partly in sympathy and partly on a dour research note, Emmis Communications ( EMMS - Get Report) lost $1.08, or 6.8%, to $14.85, and Westwood One decreased $1.08, or 4%, to $25.66.

( and Clear Channel Communications subsidiary Premiere Radio Networks share revenue produced by Jim Cramer's syndicated radio program, RealMoney.)

"Randy Michaels is very well regarded in the radio industry," said Richard Read, an analyst at Credit Lyonnais Securities. "His reassignment is obviously being interpreted negatively by the market."

Clear Channel did not state a reason for the shuffle, but the company -- which moved up its scheduled earnings announcement by a week to Wednesday -- is expected to come up with one.

Ahead of the announcement, Clear Channel said it expects to beat second-quarter guidance. Like a lot of media companies, Clear Channel will report EBITDA -- or earnings before interest, taxes, depreciation and amortization. By that metric, the company expects to earn $600 million to $615 million.

Still, today's selloff in radio stocks suggests concern about fundamentals for the industry. "The message the market is sending is that the radio business is coming back slower than hoped," said Read.

According to Read, the intrinsic growth rate for the industry is 12% to 13% of EBITDA. Stocks had traded at a premium to that level, but they are now readjusting.

"Between 1997 and 2000, economics played a role in multiple expansion for radio stocks," said Read. "But now, multiples have come more in line with lower expectations for growth rates."

Among specific concerns for the industry is a slowdown in advertising, analysts said.

"Industry sources indicate that local radio advertising may have lost some momentum recently," said Jordan Rohan, an analyst at SoundView Technology, in a research note. "Specifically, we have heard that local station general managers have become a bit nervous about meeting internal projections."