Watch out for flying insults!

A nasty battle erupted between Wall Street and academia on Thursday — with activist investor Nelson Peltz lashing out at professor Jeffrey Sonnenfeld after the Yale management expert said the hedgie’s fund performed poorly.

“His work was a bit faulty,” Peltz said of Sonnenfeld’s attack.

The professor is guilty of “cherry-picking” data about the performance of Peltz’s Trian Fund Management, the billionaire investor said in an interview on CNBC.

Sonnenfeld, in an op-ed piece published Thursday, said results of Trian lagged behind the S&P 500 in 2012 and 2014.

The timing of Sonnenfeld’s attack is crucial.

Peltz has been wrangling with chemical giant DuPont over a seat on its board. Peltz claims DuPont is a chronic underachiever.

Pointing to his stats that Trian couldn’t even outperform the S&P, Sonnenfeld wrote: “Clearly, this undermines Mr. Peltz’s argument that DuPont’s board needs Trian and Mr. Peltz to drive better returns.”

Sonnenfeld, one of academia’s leading critics of shareholder activism, said Peltz and other activists “lack the Midas touch.”

He said Trian was up only 8.8 percent in 2014 — nearly five percentage points under the S&P and up only 0.9 percent in 2012 when the S&P gained 15.9 percent.

But Peltz shot back: “He mentioned our returns for 2012 and 2014 — sort of missed 2013, when we were up 40 percent net.”

In fact, as Peltz noted, Sonnenfeld even got 2014 wrong. Trian gained 10.5 percent last year.

“It disturbs me that he can stand in front of a banner and just cite inaccurate numbers,” Peltz said in the TV interview, insisting it was a disgrace to Yale, where two of Peltz’s children went to school.

“Who are his sponsors? Who are his honorariums?” the activist asked.

Sonnenfeld also criticized Trian because five of the 11 companies where it has a board seat underperformed the S&P between the time Trian got its seat and Dec. 31.

Peltz took issue with that — noting that the stock movement typically comes before he joins the board.

The better scorecard looks at the stock movement from the time he takes an activist stake, he argued.

Stocks like Family Dollar are up 182 percent since his involvement, compared with 102 percent for the S&P, he said. Mondelez is up 162 percent, compared with the 71 percent rise for the S&P, Peltz maintained.

Independent stats seem to support Peltz.

Trian’s activist positions have far outpaced the S&P from the time of the filing, according to 13D Monitor. Active positions have gained 122.17 percent since filing, compared with 77.99 percent for the S&P.

While Sonnenfeld focused on Peltz, he also took aim at all activist hedge funds, saying the HFR Activist index gained only 4.8 percent last year, below the S&P’s 13.7 percent return.

That’s the wrong way to look at it, because the funds in that index also have passive positions, said 13DMonitor’s Ken Squire. His fund, which invests solely in activist plays, has trounced the S&P for the past three years.