Two executives of Sonova Holding AG resigned Wednesday following an inquiry into the Swiss hearing-aid manufacturer’s timeliness in issuing a profit warning, leading investigators to suspect insider trading.  

Sonova, the leader in its industry in terms of sales, is the parent company to Santa Clarita-based Advanced Bionics, manufacturer of the profitable HiRes Cochlear Implant, which Sonova acquired in 2009.  

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Advanced Bionics executives were not available for comment.  

According to a company release, Sonova Chief Executive Officer Valentin Chapero and Chief Financial Officer Oliver Walker resigned today. Andy Rihs also stepped down from his position as chairman, but remains on the board.  

On March 16, Sonova slashed its earnings forecast in light of the November recall of its Advanced Bionics cochlear implant, slowed production of traditional products and the strength of the Swiss franc.  

Yet before the announcement was made, Sonova had hired the law firm Homburger AG to look into recent activity by company directors and managers who sold about 2.4 million shares and warrants beginning February 1. One non-executive reportedly sold shares worth nearly 40 million francs (about $43 million).  

The Homburger investigation concluded that Sonova executives had failed to institute a blackout period for trading shares and options before its March 16 announcement.  

On Wednesday, Sonova stock fell as much as 9.4 percent, according to data supplied by the SIX Swiss Exchange.