These activist investors absolutely crushed it on huge trades

Pershing Square Capital last year bought nearly 10% of Botox maker Allergan and tried to push the company in to a sale to Valeant to earn a quick buck. New Jersey-based competitor Actavis stepped in with a $219 per share bid. That was nearly double what Ackman spent to invest in Allergan. Pershing bagged a $2.6 billion profit on the transaction, according to a New York Times report.

Jeff Smith spun Starboard out of Cowen Group in 2011, and has already racked up plenty of wins and some impressive returns. The fund took a stake in Darden Restaurants at an average of $51.03 a share back in 2013. He succeeded in replacing the entire board last year. By the end of trading Thursday the stock stood at $68.85. Starboard holds more than 11.6 million shares of the stock, giving the firm a paper gain of about $200 million. Smith and Starboard are now shaking up retailer Macy’s.

Rehan Jaffer founded H Partners in 2005, after spending years learning alongside legendary and incendiary activist investor Dan Loeb. He successfully executed the first “withhold campaign” earlier this year at Tempur Sealy, which resulted in the resignation of the CEO and a pair of directors. H Partners bought in all the way back in 2012, when shares were trading at less than half their value today. Now, with a stake of about 10% in Tempur Sealy closing in on a $5 billion market capitalization, Jaffer's ability to play patient and calmly pursue an overhaul of the company's board appears to have paid off.

John Paulson may be best known for his prescient pre-crisis call when he shorted subprime mortgage securities. But he’s also jumped into situations alongside other activist investors to score a quick buck. Paulson amassed a stake of 8.7% in Time Warner Cable and was pushing for a sale earlier this year. Paulson is reported to have made $250 million when Charter struck a deal to buy the cable company.

Nelson Peltz has repeatedly spent years building a stake in a company and pushing for change. This was the case in 2010, when Peltz amassed a stake of nearly 7% in Family Dollar when shares were trading for less than $40. Trian even tried buying Family Dollar before signing off on a merger with Dollar Tree, and then selling shares. Estimates put Peltz’s win in the $370 million range.