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(USA TODAY) - Last Sunday's Super Bowl blackout dimmed the stock of the Superdome's electricity supplier Friday after Entergy New Orleans took the blame for the power failure..

Stock of Entergy Corp. (ETR), parent of Entergy New Orleans, was off $1.3614 or 2.09% to $63.60 Friday.

Entergy said the problem was caused by a faulty relay that had been installed in its switching gear to prevent a failure of electric cables leading to the stadium. "During Sunday's game, the relay device triggered, signaling a switch to open when it should not have," the company said.

Company officials said the device performed without problem during January's Sugar Bowl and other earlier events. They said the device has been removed and replacement equipment will be installed.

The power failure at last Sunday's big game cut lights to about half of the stadium for 34 minutes, halting play between the Baltimore Ravens and San Francisco 49ers.

The announcement came as Entergy officials prepared to go before a committee of the City Council on Friday for questions about the outage. The council is the regulatory body for the company.