Nasdaq has promised to pay out about $40 million in cash and discounts to firms that saw losses after Facebook’s initial public offering.

But according to media reports, that’s not enough for some firms such as Knight Capital Group, which the Wall Street Journal reported estimates that its losses in Facebook’s debut total as much as $35 million.

At an investor conference, NasdaqOMX Chief Executive Robert Greifeld faced questions from Knight and others who said that compensating firms was not the best way to deal with the problem. Direct Edge Holdings LLC Chief Executive William O'Brien, the Journal reported, said that offering discounts on trading was a “shameless attempt to turn a big investor confidence-eroding event into a competitive advantage.”

On Wednesday, NYSE Euronext issued a statement saying it thinks such a plan would be “wholly inconsistent with fair practice and an undue burden on competition” and would be “tantamount to forcing the industry to subsidize NASDAQ’s missteps and would establish a harmful precedent that could have far-reaching implications for the markets, investors and the public interest.”

Meanwhile, Facebook was trading up Friday afternoon after a report from the analytics firm ComScore said that Facebook ads do have an impact on consumer behavior. Contrary to recent surveys, the company said, “Facebook earned media is having a statistically significant positive lift on people’s purchasing of a brand.”

Facebook is also working on its solution to strengthen its mobile presence, having launched both an app store and two-step mobile payment system this week. Facebook had previously said that it wasn’t sure to make money on the mobile platform, an admission that had hurt the social network, particularly as more users access it over their smartphones.

As of 2:30 p.m., the stock was trading at $27.02 — up about 2.9 percent from Friday’s opening price, but sill 29 percent down from its market debut of $38.

(Washington Post Co. Chairman and Chief Executive Donald E. Graham is a member of Facebook’s board of directors .)

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