Jana Partners is renewing its push for Markel Group Inc. to divest its venture arm while pushing the insurer to also buy back $2 billion of its shares to boost the stock.

“The current structure produces sub-peer shareholder returns, creates no unique value and warrants a discounted multiple,” Jana Managing Partner Scott Ostfeld and Managing Director Jimmy Ganas said in a letter to Markel’s board Thursday reviewed by Bloomberg News. “The need for change is clear.”

While Jana lauded the “dramatic improvement” in the company’s insurance operations under new leadership, the activist investor argues that its “ongoing poor performance” can no longer be attributed to that unit dragging things down.

Jana also said the market fully understands and has clearly rejected Markel’s business model of combining insurance with the ventures arm, which has backed health-care, construction and a broad range of other types of businesses through the years.

“Markel’s strategy has also failed to deliver promised diversification benefits,” Ostfeld and Ganas said. “Specialty insurers and industrial holding companies that stayed focused (or elected to spin off non-core assets) have outperformed Markel.”

bloomberg.com - Jana pushes markel to divest ventures buy back billion shares