Procter & Gamble should not split into two — a beauty & grooming unit and household care business, a source close to the company said.

The subject of a split of the country’s largest consumer products company was buzzing around Wall Street yesterday after activist investor Bill Ackman revealed his Pershing Square firm had made its biggest ever initial investment — taking an undisclosed stake in the struggling consumer products giant.

“There’s real evidence that splitting could hurt them,” the source said.

Ackman did not make his intentions clear after his stake was made public.

Besides possibly pushing for a split, he likely has CEO and West Point graduate Robert McDonald in his sights.

“He will probably agitate for a new board and CEO,” another source who advises consumer companies said.

P&G — maker of Gillette, Duracell and Tide among dozens of other brands — has cut its profit forecast three times this year.

What the source found fascinating was shareholder activists today are not finding any company too big to target.

P&G’s shares rose 3.8 percent yesterday to $63.70, giving it a $175 billion market capitalization.

A second activist investor, Ralph Whitworth, meanwhile, has taken a large stake in $109 billion PepsiCo, which is under some pressure to split its business in two — snacks and beverages.

Kraft is in the process of splitting its businesses to boost its value.

Bloomberg reported yesterday that P&G’s board is already putting pressure on McDonald — who has been CEO since 2009 — to resign.

P&G’s difficulties stem from not hedging properly against rises in commodity prices, and then during the recession not being able to mark down the cost of its goods, the second source said.

Ackman did not return calls for comment.