Is eBay (EBAY) - Get eBay Inc. Report about to speed up its stock-buyback program?

That's what recent gains in shares of the auction giant might be indicating. The stock has climbed more than 12% over the last five trading sessions, closing Wednesday at $36.71. The

Nasdaq

, meanwhile, has inched up only 2% over the same period.

This latest run-up comes even as eBay competitors grow bolder, and during what observers say is usually a weak time of the year for the company. This week,

Amazon.com

(AMZN) - Get Amazon.com, Inc. Report

announced that it would launch its own payment service, which will be a rival to eBay's PayPal.

Meanwhile, online retailer

Buy.com

recently introduced Garage Sale, an application that lets users buy and sell goods over popular platforms like social networking site Facebook.

In addition, this time of year historically has been when investors turn their backs on the stock. "And to top it all off, we are in what is usually EBAY seasonal lows," writes the blog "Only eBay."

But a filing by eBay last Friday with the

Securities and Exchange Commission

has some investors expecting another leg up. The filing disclosed that eBay doubled its credit line with

Bank of America

(BAC) - Get Bank of America Corp Report

to $2 billion, with an option to increase it to $3 billion in the future, notes American Technology Research analyst Tim Boyd.

Boyd says the market is beginning to price in one of three options: that the company will accelerate its stock-buyback program, make an acquisition, or declare a one-time dividend with the extra funds on hand.

But a closer look at all three scenarios suggests a stock buyback is the most likely. And thankfully for eBay investors, it also may be the best outcome.

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A one-time dividend is the least likely because eBay switched to a restricted stock-compensation plan in January, Boyd says. That makes options granted over the year ineligible to receive a dividend, and would complicate matters.

Rumors of an acquisition also are swirling, says Boyd, and the likely candidates tend to be

Yahoo!

(YHOO)

,

IAC/InterActiveCorp

(IACI)

, minus its Home Shopping Network business, and

Bill Me Later

, a site that lets user defer payment for items.

An acquisition of Yahoo! could be very attractive, says Boyd, given the enormous amount of traffic the combined companies would share, and the potential for working together on the advertising front.

But it's difficult to see how the addition of another maximum $2 billion in credit could be seen as a substantial step toward buying Yahoo!, which commands a market cap of $32 billion. And Yahoo! CEO Jerry Yang said the company hopes to go it alone, during its last quarterly conference call.

An IAC or Bill Me Later deal, while much more feasible with another $2 billion on hand, would make much less strategic sense for eBay. IAC is worth about $7.6 billion, with the HSN shopping business accounting for half its revenue.

If the HSN were to be spun out, eBay -- with $3.6 billion in the bank -- could easily make a bid for it. Bill Me Later, which is privately held and does not have to disclose its value, also would likely be easily within eBay's price range.

But an IAC deal would be more hassle than it's worth. IAC is already a sprawling conglomerate by itself. Combining it with eBay, which itself has at least three different lines of business, would create a hard-to-manage entity that would be tough for Wall Street to value.

And two of IAC's most prominent business lines would overlap with eBay's own efforts. IAC owns online-ticketing site TicketMaster and local services marketplace ServiceMagic. eBay's acquisition of StubHub already has put it in the ticket business, and its recent U.S. launch of local commerce site Kijiji could make it a player in local services.

eBay is also unlikely to acquire Bill Me Later. PayPal just launched its PayPal Pay Later service at the beginning of the month, which is a direct knock-off of Bill Me Later. eBay likely would go it alone before shelling out for the service.

That makes an accelerated buyback the most likely outcome. And the buyback could be big, Boyd believes.

The additional credit facility -- which Boyd says eBay has told him can be used to make share repurchases -- combined with the cash it has on hand and its cash flow over the next year, could allow eBay to buy back $9 billion worth of its own shares.

And while Boyd hardly expects eBay to go all out, "even $5 billion would be a very material amount."