Skadden Arps Slate Meagher & Flom is leading a heavyweight line up of advisers on Microsoft's $44.6bn (£22.6bn) approach for web rival Yahoo.

The New York firm is advising Yahoo on the deal, while Simpson Thatcher & Bartlett and Cadwalader Wickersham & Taft are understood to be acting for Microsoft.

Palo Alto corporate partner Kenton King is leading the Skadden team. King has a longstanding relationship with Yahoo and has advised the company on numerous corporate deals in recent years, including its $350m (£177m) purchase of Zimbra and the acquisition of a 40% stake in Alibaba.com in a transaction valued at more than $4bn (£2bn).

King said: "We have acted as longtime outside counsel for Yahoo in a range of issues, so we were brought in right away."

Microsoft's appointment of Simpson Thacher could be seen as a blow to Sullivan & Cromwell, which has traditionally been viewed as one of Microsoft's main advisers and has defended the company in numerous antitrust cases.

Global antitrust chief Rick Rule is leading the Cadwalader team alongside antitrust partner Jonathan Kanter and senior associate Andy Forman.

Simpson Thacher has a close relationship with buy-out house Blackstone, one of Microsoft's advisers on the deal. Microsoft has also used firms including Heller Ehrman and Covington & Burling in the past.

Microsoft announced on Friday (1 February) that it has proposed to the Yahoo board of directors to buy all outstanding shares of Yahoo's common stock for $31 (£16) per share, 62% above the closing price of the shares the previous day.

Microsoft suggested that a combined company would have a position to compete with Google, the search engine that currently dominates the online advertising market. Microsoft estimates that Google holds around a 75% share of this market, worth $40bn (£20bn) in 2007.

Microsoft general counsel Brad Smith said: "Given its super-dominant market share, Google is clearly prevented by the antitrust laws from buying Yahoo or buying this business from Yahoo."

The proposed tie-up is potentially one of the largest and most complex corporate takeovers ever attempted in the US and any deal is set to face intense scrutiny from competition regulators on both sides of the Atlantic.

Google has already voiced its opposition to the merger on antitrust grounds, with Google's chief legal officer, David Drummond, claiming that Microsoft has "frequently sought to establish proprietary monopolies – and then leverage its dominance into new, adjacent markets" in a blog posted on 3 February on the internet giant's website.

The deal could face further complication as Microsoft is viewed as likely to proceed with a hostile offer if the Yahoo board refuses to recommend its bid, potentially triggering a highly lucrative battle for control for advisers.

Heller Ehrman corporate partner Richard Eaton commented: "Clearly this is hugely significant. The only other deals of similar size would be AOL-Time Warner or Oracle. This shows how dominant Google has become and what others need to do.

"There have been very few hostile technology mergers [but] it is an unsolicited offer so it is possible. Some serious fees [would] go to the firms involved."

Click here to read Drummond's blog in full.

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