U.S. antitrust regulators appealed a court ruling on Friday which denied their request to block the largest natural grocer, Whole Foods Market Inc., from acquiring its closest rival, Wild Oats Markets Inc.

Late Thursday, U.S. District judge Paul L. Friedman rejected the Federal Trade Commission’s argument that the combination of both companies would restrict competition. The FTC had sought a preliminary injunction against the $565 million deal.

In its appeal, the FTC also asked the U.S. District Court for the District of Columbia to prevent the deal from closing until the outcome of the appeal had been decided, a request denied by the judge. Another FTC request is still pending before the U.S. Court of Appeals for the D.C. Circuit.

The judge's ruling was seen positively by investors who sent shares of both firms higher in Friday trading. Whole Foods shares jumped $3.13, or 7.60 percent, to close at $44.30 on the Nasdaq Stock Market. Wild Oats shares rose $2.71, or 17.9 percent, to $17.92