Hedge fund titan Carl Icahn announced via Twitter that he had purchased a stake in the oil and gas exploration company Talisman Energy.
Though Talisman's stock has been virtually flat since late 2011, the share price spiked 6 percent in extended-hours trading.
"Disclosed approx 61 million share position in Talisman Energy. May have conversations with mgmt re strategic alternatives, board seats, etc.," Icahn's tweet said.
According to a filing with the SEC, he bought 61,554,602 shares, or a 5.97 percent stake, for $277 million.
Icahn announced in August via Twitter that he was buying Apple stock and said he intends to push for massive payouts to shareholders.
An hour after that post, Apple's market capitalization rose by $17 billion, according to Fortune magazine, proving that the heavyweight can shake up the market with just 140 characters.
—By CNBC's Karma Allen. Follow him on Twitter @iam_karma.