Get ready for

Google

(GOOG) - Get Report

to pull another rabbit out of its hat.

A boatload of new Google shares is due to come on the market next week. The prospect of so-called lockup expirations has sparked chatter that the stock -- which has more than doubled in less than three months -- has topped out.

But some observers shrug off the lockup talk, pointing out that Google investors have heard this all before. These people say demand for Google shares will l likely neutralize any lockup-related selling -- at least for now.

"You only have four or five people who own the stock," says Frank Husic, managing partner of Google shareholder Husic Capital Management, in a reference to a handful of institutions with 500,000-share-plus holdings in the search-engine company. "How many more people are going to own it?"

Next Thursday, a post-IPO lockup on 39.1 million shares of insider-owned Google stock is slated to expire. The event could more than double the number of Google shares that are freely tradeable in the public markets. Skeptics have pointed to coming lockup expirations as obvious weights on the stock price.

But the likely desire of other institutions to get a piece of Google, Husic suggests, will offset any new supply created by the expiration. "People realize there could potentially be demand for the stock when the lockup comes off," he says. "It's these two forces playing against each other."

Concern about the expiration, along with worries that the stock's price has gotten out of control, already appear to have had an impact on the stock price.

From an offering price of $85 per share, Google zoomed as high as $201.60 last week. By Tuesday evening, however, the stock had retreated 16% from that level to $168.70; on Wednesday, shares were up $1.25 to $169.95.

Signaling some of the market's worries about Google,

UBS initiated coverage of the stock last Friday with a reduce rating and a $160 price target.

But, arguing that the Nov. 18 expiration's impact on the stock is overrated, Credit Suisse First Boston analyst Heath Terry raised his price target on Google from $177 to $225. Terry has an outperform rating on Google; his firm was one of the company's lead underwriters.

"While we expect that the uncertainty the impact these expirations will have will create plenty of volatility in shares of GOOG, we believe the ultimate impact on the stock price once it is all said and done will be significantly less than our gauge of investors' expectations," writes Terry in his Wednesday note.

"These lockup periods are only one of the limitations on insider stock sales," says Terry. "Quarter-end black out periods, management's structured selling plans, and the company's employee option vesting schedule will all limit the amount of stock sold. ... We don't expect significant sales by the executive officers and directors, who control 67.6% of shares outstanding, given the dual class structure and the lengths management went to in order to maintain control."

Going into next week, Google has a float amounting to no more than 27.2 million shares,

according to

TheStreet.com's

calculations -- stock worth $4.6 billion at Wednesday's prices.

For purposes of comparison,

Yahoo!

(YHOO)

-- the Google competitor and fellow dominator of the Internet advertising market -- has a float of 1.1 billion shares worth more than $40 billion.

Further cutting down the supply of Google stock are the disclosures, at various times, that

Fidelity

,

Legg Mason

,

Vanguard Group

and

Fred Alger Management

have owned a total of 11.8 million Google shares, leaving only 15 million or so shares -- roughly $2.5 billion of stock -- for everyone else.

While the supply-demand imbalance could be eased by further lockup expirations scheduled for December, January and February, Google's fans point out that the stock has something else going for it: the company's underlying growth in the fast-growing business of online search advertising.

Husic, for one, is bullish about the prospects for growth in the local dimension of search advertising: Customers using Google and other search engines to find nearby businesses, not just national marketers.

More localized search-engine advertising "will open it up for a very large number of new customers to come in and participate," he says. "Really, it's going to be an absolute blowout when your toilet overflows and you go and find Joe's Plumbing" online, he says.