The U.S. Securities & Exchange Commission is investigating what exactly Systemax Inc. found following a whistleblower investigation of its Miami operation, a situation that led to the resignation of the company’s top e-commerce executive.

In a recently posted regulatory filing, Systemax, No. 23 in the Internet Retailer Top 500 Guide, disclosed that the SEC has initiated a formal investigation into certain matters discovered by the company during its internal investigation of its Miami operations.

The board of directors for Systemax voted May 3 to accept the resignation of Gilbert Fiorentino, the former CEO of its technology products group.

Systemax has had little to say publically about the specific reasons for why Fiorentino resigned as the executive in charge of its biggest business unit, which last year recorded sales of $3.33 billion, up 12.5% from $2.96 billion in 2009. But on April 18 Systemax placed Fiorentino on administrative leave, announced plans to terminate his employment and named Robert Leeds, the founding CEO of its technology products group, as interim CEO of that operation. At the time Systemax also said it was completing what it described as an investigation of anonymous whistleblower allegations related to  its Miami operations, which reported to Fiorentino. Systemax has not said publicly what that investigation revealed, other than it covered a period of years.

Systemax, a multichannel retailer that owns and operates TigerDirect.com and CompUSA.com, isn’t commenting in detail on the SEC investigation. “The company intends to cooperate fully with the SEC in its formal investigation and does not expect to comment further on developments related to this matter and disclaims any intention or obligation to update any of the information” Systemax says in its regulatory filing.”