Bill Ackman’s Pershing Square Capital Management is reportedly taking a large position in payroll and benefits giant Automatic Data Processing, sending the company’s stock to a record high.  The activist investor has been quietly building a position for some time, according to a Reuters article citing two unidentified individuals familiar with the matter. Since early this year, Ackman has cryptically referred to two new portfolio positions that have been working out very well, and signaled in early May that an unidentified new position in the fund accounted for approximately 5% of its capital. Ackman has also hinted at plans to...