Apollo Global Management is the buyer reportedly paying $42 a share, which is 56 percent more than the company's closing price Friday, reported CNN Money.
The news led to ADT shares rising over 50 percent in early trading Tuesday, according to CNN Money.
ADT and home security firm Protection 1, already owned by Apollo, will merge, said CNN Money.
The ADT stock before the purchase by Apollo had been down 30 percent, and the company's sales at the start of February were not as forecast, reported CNN Money.
Click here to read the CNN Money story.
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