Shares of Facebook (Nasdaq: FB), the No. 1 social networking site, rose as much as 5 percent on Friday after a preliminary report by comScore (Nasdaq: SCOR) that its advertisements are effective.

Facebook shares surged as high as $27.76 before settling back to close at $27.50, up 79 cents or 3 percent,Shares of the Menlo Park, Calif.-based website had plunged as much as 32 percent in the past three weeks on concerns ad revenue gains and earnings will decline. They were priced at $38 in their May 17 initial public offering.

The comScore report determined Facebook ads for earned media help to move merchandise. It follows an earlier survey by Reuters Ipsos that found people were paying less attention to Facebook and relied upon it less for advertising.

Despite the rise, Facebook's performance in the three weeks since its IPO has set records. The loss in shareholder value is likely the largest ever for a company.

Facebook's market capitalization now is only $57.94 billion, compared with $104 billion at the outset. For CEO Mark Zuckerberg, 28, the paper loss is also a record: since the IPO his loss amounts to about $5.3 billion, although his Facebook shares are still valued around $13.8 billion.