Shares of popular search engine Google soared in after market trading and could portend a close above US$500 for the first time in months.

The company's stock ended after-market trading at US$525.96 on Thursday, up 17 percent, or US$76.42 above its close in regular trading hours on the same day. Google reported earnings that beat analyst expectations after regular stock trading closed.

Google's stock closed at US$449.54 during normal hours. The last time the stock closed above $500 during regular trading was on February 22, at US$507.80. On February 25, the shares traded as high as US$506.50, but ended the day at US$486.44. Because fewer shares are available during after-hours trading, share prices can push higher on positive results released after the market closes.

On Friday, Google shares may not hit the same price as Thursday's after-market, but there is a good chance they will rise significantly, given the after-market surge.

The shares have not hit US$500 since that time, but Friday could be different. Stocks often follow what happens in after-market trading, but shares may not soar as high and news overnight could also affect the stock market.

Google's revenue soared 42 percent year-on-year in the first quarter to US$5.19 billion and it posted net income of US$1.31 billion. The company's pro-forma net income, which excludes certain items, was US$4.84, which beat analysts' expectations of US$4.52 per share.

The company also reported paid-click growth of 20 percent compared to the same time last year, higher than the figures reported by third parties. Negative reports on Google's paid-click growth from Internet watchers such as comScore and Hitwise had been a key factor in the stock's decline over the past few months.