Billionaire investor Carl Icahn's proxy fight for Yahoo is aimed at reigniting merger talks between the Internet company and Microsoft, but he may have to prepare a backup plan in case Microsoft is unwilling to return to the bargaining table.

After Microsoft walked away from its US$44.6 billion bid to acquire Yahoo, the company has been clear, publicly at least, about moving on, and executives said they are not interested in purchasing Yahoo anymore.

"It's not clear that Microsoft is still at the [bargaining] table," said Ned May, an analyst with Outsell. "That's a bit of a problem."

If Icahn can't woo Microsoft back as a Yahoo suitor, he may end up in the position of being the director of a company that no one wants to buy. And as Icahn has never seemed very interested in actually running someone else's business, this would put him in a rather risky situation.

Having made his $14.5 billion fortune by taking calculated risks, however, it's likely Icahn is preparing himself for the worst-case scenario. A source close to the billionaire investor said he may be consulting with IAC/InteractiveCorp CEO Barry Diller as he mounts his proxy battle for Yahoo.

One possible topic of the talks could be a plan to sell off parts of Yahoo to IAC, which owns Ask.com, a competitor to Yahoo's search engine.

IAC has faced its own troubles of late as it prepares to split itself into five pieces, and could be bolstered by acquiring Yahoo's advertising network and users.

However, it's unlikely that IAC, with a market cap of $6.6 billion, could afford such a deal, although it's clear Diller is interested in expanding his company's media properties, however far-flung they may end up being. On Thursday, IAC's Ask.com announced plans to buy Lexico Publishing Group, the owner of Dictionary.com, Thesaurus.com and Reference.com.

It wouldn't be surprising if Icahn also was speaking with other executives to prepare himself for the event that Microsoft won't return to negotiate a deal. Infrastructure Corp. has been rumored as a potential suitor now that Microsoft is out of the picture; however, on a May 8 conference call, executives said the company is not in talks to purchase Yahoo at this time.

News Corp. did not reply to a request for comment on Thursday.

One analyst noted that "cash is pretty tight these days," which might make it risky for any company to invest in Yahoo if Microsoft won't bite.

Moreover, "Yahoo worked pretty hard to find other suitors to counter Microsoft, and were apparently unsuccessful in lining those up," said the analyst, who asked not to be named. If no one besides Microsoft came forward during the two months it haggled with Yahoo over a price, it's unlikely anyone would be willing to buy the company now, he said.