Sotheby's looks to bring the hammer down on Dan Loeb

The 270-year-old auction house has come out fighting against the hedge fund king's attack on its boardroom

Dan Loeb has a fearless and brash style (Getty Images)

When the US hedge fund star Dan Loeb started out as an activist investor he waged war in online chatrooms under the alias Mr Pink, one of the mobsters in Quentin Tarantino's film Reservoir Dogs.

The billionaire's targets may now be huge companies such as Sotheby's, Apple and Yahoo, but his public attacks on underperforming companies,usually in acerbic letters to their managers, are no less violent. He even upset Hollywood favourite George Clooney last year after getting Sony's movie business in his sights.

But this week Sotheby's, his latest target and the oldest listed company on the New York Stock Exchange, fired back. The auction house rejected claims of poor management and instead, in a 53-page Powerpoint presentation, detailed how companies in which Mr Loeb has bought shares and got on to the board have underperformed.

Sotheby's said his investments are purely "self-interested transactions" and pointed to Yahoo, where his hedge fund Third Point ousted the chief executive and made more than $1bn (£600m) from buying and selling the shares.

Mr Loeb, an art collector himself, is arguing that the 270-year-old auction house is like an "Old Master painting in desperate need of restoration" with an overpaid board that enjoys too many perks. He accuses its chairman and chief executive, William Ruprecht, who has been at the house for 33 years, of squandering cash on lavish dinners, trips and "elite country club" memberships.

Mr Loeb is now Sotheby's biggest investor, with a 9.6 per cent stake, and he wants to put his own people on the board. In February he nominated three directors, including himself, in a proposal on which shareholders will vote at the annual meeting next month.

Sotheby's directors think they have already rewarded shareholders and have vowed to fight. In their attack on Mr Loeb they say he and his nominees "would add no incremental, relevant skills" to the board and would only be "advocates for Mr Loeb's interests rather than those of ALL shareholders".

They claim he is a "disruptive director" and only interested in the short-term gains for himself.

Sotheby's announced a special one-time dividend in February of $4.34 a share and has plans to sell property to raise more funds. Its 2013 full-year earnings were up 20 per cent to $130m, but the growth was below previous years, despite a booming art and antiques market globally.

But Mr Loeb, who is a fitness enthusiast and one-time "surf dude", has his supporters. The hedge funder Mick McGuire's Marcato has a 6.6 per cent stake in Sotheby's and supports Mr Loeb's plan, which includes increasing shareholders' returns by making Sotheby's more competitive with rival Christie's. Mr Loeb, who is based in New York but grew up in California, wants more online sales, better "curated" auctions and bigger funds to buy more artworks.

One of Mr Loeb's supporters, Anthony Scaramucci, the founder of Skybridge Capital, which invests vast sums in Third Point, loves his style. Mr Scaramucci told Vanity Fair recently that Mr Loeb is "the guy that would chew through the wallboard to create a return for his investors".

Not every outspoken investor is on Mr Loeb's side. Recently the US short-seller Jim Chanos, founder of Kynikos Associates, declared that he was shorting the stock – meaning he thinks Sotheby's share price will fall further. He believes that the art market is in a bubble, and said: "Anybody who buys art should be looking to hedge it right now … the contemporary market has gone bonkers."

Mr Chanos might not agree with Mr Loeb's viewpoint. But Third Point – named after an area in California where Mr Loeb used to surf – is under pressure to perform itself. His Yahoo performance was a winner, but 2014 is not turning out as well. According to reports last month Third Point is up only 3.3 per cent, below peers such as Bill Ackman's Pershing Square, which returned 10.7 per cent in the quarter.

Mr Loeb's fearless and brash style has even shocked other hedge funders, who say he is so extreme he makes them look like angels.

Despite the dip in performance, Mr Loeb has been in worse situations. In 2007 his funds were down more than 30 per cent. But investors stood by him and he clawed his way back from the brink.

Mr Loeb's tactics might make other corporate raiders look like Mother Teresa, but it is down to shareholders on 6 May to decide whether he is a saviour or a sinner for Sotheby's.