(Reuters) - Tiffany & Co on Sunday said Frederic Cumenal has stepped down as chief executive officer, after what the upscale jeweler called disappointing financial results. The retailer said its chairman and previous chief executive, Michael Kowalski, would serve as interim CEO while the board of directors seeks a new CEO. "The Board is committed to our current core business strategies, but has been disappointed by recent financial results," Kowalski said in a release.