Hellman & Friedman spent $1.38 billion to acquire a 7.5% stake in Splunk according to a statement in March 2022. That translates as $116 per share and yields 35% return based Thursday's deal price of $157 per share.

Hellman & Friedman did not immediately respond to a request for comment.

Starboard revealed it was an investor in Splunk 12 months ago and pushed for changes to improve the company's growth and profitability, highlighting it was a valuable acquisition target.

The hedge fund paid somewhere in the mid-$80s per share for its stake, according to people familiar with the matter, representing a close to 85% return.

Starboard's latest disclosure shows it owned a 2.46% stake in Splunk as of the end of June, that would be worth $628 million at the Cisco deal price, although the exact amount of shares it had bought and sold prior to Thursday could not be learned.

Starboard did not immediately respond to a request for comment.

A major investor that did less well was Silver Lake. The private equity firm stands to roughly break even after spending $1 billion on a convertible bond in 2021 with a conversion price of $160 per share. It expects to record a small profit after adjusting for a customary make whole provision at deal closing as scheduled in 2024.

Silver Lake declined to comment.

(Reporting by Milan Vinn in New York and Svea Herbst-Bayliss in Rhode Island; Editing by Kirsten Donovan)

By Svea Herbst-Bayliss and Milana Vinn