LOS ANGELES (AP) — Concert promotion giant Live Nation Entertainment Inc. said Thursday that ticket sales for the Top 100 bands are down 12 percent in the first half of the year, and sales will likely fall further in the second half. Shares of the company plunged.Shares dropped $1.84, or 16 percent, to $9.59 in afternoon trading Thursday. That’s the lowest point since before Jan. 25, the day it announced it had consummated its merger with Ticketmaster Entertainment following approval by the U.S. Justice Department. Chief Executive Michael Rapino told investors in New York that the weak economy has taken its toll on the concert industry. But even he appeared surprised at the massive sell-off his presentation had caused. “We had a real buzz kill at about Slide 9 when I saw the e-mails go out,” he said. Executive Chairman Irving Azoff, who presented via video conference, chided investors for the sell-off. “I’m hoping that what I’m seeing as all you guys e-mail back to your offices to dump the stock isn’t indicative of the fact that we have a group of investors that are so shortsighted,” Irving said. The company said a further 15 percent drop in concert ticket sales for the Top 100 tours could occur in the second half. Adjusted operating income for 2010 is expected at $405 million, down from $445 million last year, despite the benefits of its merger this year with Ticketmaster. A rash of cancellations from bands has also hurt sales. U2′s postponement of its tour until next year will cost the company $6 million this year.