Mark Walter, the billionaire CEO of Guggenheim Partners who recently added the Los Angeles Lakers to a sports portfolio that already included the Dodgers, is now facing a far less glamorous kind of attention. Federal prosecutors in Manhattan are investigating potential financial improprieties across his sprawling investment empire, which manages north of $362 billion in assets.

The probe, which reportedly began last year, has recently expanded in scope. The Securities and Exchange Commission has launched its own parallel inquiry into Guggenheim’s asset-management unit.

What prosecutors are actually looking at

The federal investigation centers on Guggenheim Partners’ money-management arm and two insurance companies tied to Walter: Delaware Life Insurance Co. and Clear Spring Life and Annuity Co. The probe has grown beyond its initial parameters to encompass additional transactions involving Walter personally.

On the SEC side, regulators are zeroing in on a specific piece of real estate: an $85 million Malibu property co-owned by Walter and an entity called ABS Capital Co. LLC. The commission is also examining several other transactions involving ABS Capital.