(March 27): Shares in Australian department-store chain Myer Holdings Ltd rose the most on record after a 10th of shares outstanding changed hands about 30 minutes before markets closed in Sydney.

The stock climbed 18 percent, the most since Melbourne-based Myer was taken public by private-equity firm TPG Capital LP in 2009. Trading volume soared after the 82.1 million share block crossed at 3.28pm and ended the session at 117.4 million shares. The buyer of the stake, who paid A$1.15 a share, is required by local regulations to make an announcement within two business days.

Myer has lost 70 percent of its market value since the IPO as Australian consumers increased spending at specialty stores and on the Internet. Profit, excluding some items, has fallen every year since 2010, driving investors to bet against the struggling retailer. Today’s block trade unraveled some of those bets.

“This is one of the most heavily shorted stocks on the market, and it’s started a scramble,” said CMC Markets chief market strategist Michael McCarthy. “This is a real pain for short sellers.”

Short interest in the stock was about 15 percent of shares freely available to trade as of March 23, according to data from IHS Markit. Myer is among the 10 most shorted stocks on the benchmark S&P/ASX 200 Index, according to data compiled by Bloomberg.

The trading also triggered speculation of a deal. Solomon Lew, chairman of Myer rival Premier Investments Ltd, may be involved in the transaction, the Australian Financial Review reported, citing people it didn’t identify.

Representatives of both companies declined to comment.