NEW YORK (Bloomberg) — Shares of Google Inc. passed $500 for the first time after profit almost doubled in the last quarter and analysts predicted the stock may gain another 20 percent.Google, which began trading at $85 a share in August, 2004, joins a group of six other companies whose shares trade above that level. That set includes Berkshire Hathaway Inc. and Washington Post Co. Google shares have jumped 22 percent this year and rose $12.01 to $507.06 at 1.45 p.m. New York time in Nasdaq Stock Market composite trading.

The stock’s advance values Google at 62 times earnings, more than double the average for the Standard & Poor’s 500 Software & Services Index. Investors are betting Mountain View, California- based Google will continue to increase sales and profit as it captures rising demand for advertising linked to search results.

“Expectations for the online advertising market overall remain very robust,” said Sasa Zorovic, an analyst at Oppenheimer & Co. in Boston who rates the shares “buy.” “Revenue continues to grow very nicely.”

Google reached $400 a year ago. Standard & Poor’s said last week that the stock is set to replace HCA Inc., the biggest US hospital operator, in the S&P 100.

All but one of Google’s largest 10 shareholders increased their holdings last quarter, data complied by Bloomberg show. Fidelity Investments, the world’s biggest mutual-fund company, boosted its stake by almost a million shares to 25.5 million.

The rise gives Google a market value of more than $155 billion, placing it third behind Microsoft Corp. and Cisco Systems Inc. among US technology companies. Yahoo! Inc., the second largest Internet search engine, is worth about $37 billion.

Yahoo’s stock trades at 55 times earnings and Microsoft at 22.9 times, according to Bloomberg data.

“Google remains our top pick in the Internet space,” Heath Terry, an analyst at Credit Suisse in New York, wrote in a note last week. Along with Piper Jaffray & Co.’s Safa Rashtchy and Citigroup Inc.’s Mark Mahaney, Terry predicts the shares will top $600.

Of the analysts who follow Google, 33 recommend buying the shares, four advise holding, and one, Guzman & Co.’s Philip Remek, suggests selling. Google spokesman Jon Murchinson declined to comment on the company’s stock price.

Other companies that trade above $500 include Seaboard Corp., a pork processor and cargo shipper, home-builder NVR Inc., White Mountains Insurance Group Ltd., a Bermuda-based insurer, and the Chicago Mercantile Exchange, the biggest US futures market. They all trade on the American or New York Stock exchanges.

Google went public when it sold 19.6 million shares on August 18, 2004. The company sold another 14.2 million shares at $295 apiece in September last year.

The surging stock price has made billionaires out of Larry Page and Sergey Brin, who founded Google in 1998 as graduate students at Stanford University. Page and Brin, both 33, have each sold 20 percent of their holdings since the company’s initial public offering, reaping $2.2 billion apiece, according to the Washington Service, which tracks inside sales. They each still hold 30.6 million shares, worth about $15 billion each.

Google has beaten analysts’ profit estimates in all but one of its nine quarters as a public company. A combination of marketers spending more of their ad budgets online and improvements to Google’s advertising software contributed to those results.

Internet ad spending in the U.S. jumped 33 percent in the third quarter, signalling a record year, the Internet Advertising Bureau said last week. Online ad purchases, which have increased for eight consecutive quarters, rose to $4.2 billion, the most ever in a single quarter, from $3.1 billion a year earlier, the IAB said, citing data from PricewaterhouseCoopers LLP.