About 23 hedge funds held a combined 1.2 percent in Kraft on Wednesday before the bid was announced on Friday. The 5.3 percent rise took the stock to an all-time high.
Multi-manager firms Millennium Management, Citadel and Balyasny Asset Management were among those holding the stock, Reuters Eikon data shows.
It is not known when they entered their positions or what type of investment strategy they were pursuing.
However, investors piled into Kraft the day before the announcement with 10.6 million shares changing hands on Thursday compared with 2.4 million on average the previous week.
"On the event-driven side, (hedge funds) are now building long exposures on Unilever and ... short Kraft the acquirer," said Philippe Ferreira, senior cross asset strategist at Lyxor Asset Management.
Volumes traded in Unilever rose from 2.4 million shares on Thursday to 21.3 million on Friday.
Event-driven hedge funds, which aim to profit from company mergers and acquisitions, made gains of 16.7 percent in 2016, according to data from industry tracker Hedge Fund Research. The average hedge fund made just 6 percent over the same period.
"You're starting to see managers launching pure mergers and acquisitions hedge funds," said Hilmi Unver, partner at Swiss hedge fund investor Notz Stucki Group,
Boston-based Adage Capital Management, $1.4 billion Weiss Multi-Strategy Advisers and LMR Partners, also held positions in Kraft Heinz before the announcement.
Funds contacted by Reuters declined to comment or did not respond to requests for comment.
(Reporting by Maiya Keidan; Editing by Ruth Pitchford)
By Maiya Keidan