KXIP vs KKR Live Score

Ackman is also seeking to replace the current chief executive officer. "However, ADP has a clearly defined board nomination process, and the 2017 deadline for director nominations has been public for almost a year". Everyone's done it: "While I am always praising of you as a person and an intellect if I agree to say something it will be supportive of the company and critical of you".

"ADP is open to constructive input from our shareholders, and our board respects the right of shareholders to nominate directors", the company said in its statement. ADP's board includes 10 people. After spending the better part of two years trying to convince just about anyone his investment in Valeant was a good one, Ackman more recently referred to the effort at the controversial drugmaker as a "huge mistake".

Based on extensive research and due diligence, Pershing Square believes that there is an enormous opportunity to improve the operating performance of ADP by accelerating growth, improving the quality of ADP's software and service offerings, dramatically reducing operating costs, and increasing efficiency.

This isn't the first time Ackman has owned a stake in ADP.

But ADP is pushing back, touting its total shareholder return of 202% since Rodriguez took the helm and contrasting it to Pershing's return of 29%.

Pershing Square has long admired ADP's business. Pershing Square intends to file a Schedule 13D on Monday, August 7, 2017.

In pre-market activity, shares were trading at $114.99, up 2.88 percent. From the beginning of the year through July 26, the day before Bloomberg News reported on Pershing Square's stake, the company's stock had risen about 3 percent, compared to about 9 percent for the Standard & Poor's 500 stock index. The stock is up about 8.2 percent this year, valuing the company at $49.8 billion.