Automatic Data Processing (ADP) - Get Report stock surged 9% by Thursday's close following a report that billionaire investor Bill Ackman and his Pershing Square Capital Management were building a stake in the business outsourcing company, CNBC reported.

Pershing previously owned ADP shares from 2009 to 2011. It has now acquired an undisclosed number of additional shares, according to documents filed last week.

Pershing is known for big bets that push some companies to make major changes. The hedge fund succeeded with a recent General Growth Properties (GGP) stake and Wendy's Co (WEN) - Get Report venture, but failed with Valeant Pharmaceuticals (VRX) and exited the position this year.

ADP stock had been climbing Thursday morning following a positive second quarter earnings report. The stock is up over 13% this year.

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