Just as Yahoo prepares to unveil its long-awaited ad program (fka Apex and AMP) within the next few months, it’s losing a top ad exec: Todd Teresi, SVP for its Publisher Channel, is leaving the company, Valleywag reported. Teresi was put in charge of handling Yahoo’s (NSDQ: YHOO) Publisher Channel last year. The group is responsible for managing off-network partnerships like WebMD, Turner & Cars.com.

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Valleywag suggests some sort of corporate rivalry behind Teresi’s departure, as Mike Walrath, SVP, Yahoo Advertiser Marketplace Group, prepares to move from New York to San Francisco. Walrath, the former CEO of Right Media, which Yahoo acquired in full last year for $680 million, told Valleywag the move is a “lifestyle decision” and dismissed any corporate machinations.

Sources told paidContent that Teresi is leaving the company after nine years to take on an executive role at a “venture-backed company”—not because he was being pushed out. A Yahoo rep said that Walrath is not going to be taking over Teresi’s responsibilities and a replacement has not yet been named. The rep insisted that none of the Publisher Channel’s projects would be disrupted as a result of Teresi’s exit, as Yahoo has “a deep and talented management team.” I spoke with Teresi in June at a Yahoo press luncheon and he said he had been working on expanding Yahoo’s video syndication partnership with CBS.