Bill and Gayle Cook, the co-founders of medical-device maker Cook Group, passed ownership of the company to their son, Carl, to avoid estate taxes prior to Bill Cook’s death in 2011, according to a biography of the patriarch.

“We had to bypass Gayle to get the stock to Carl now. That took a long time and a lot of planning and work,” Bill Cook is quoted as saying in “The Bill Cook Story,” a 2008 biography written by Bob Hammel for Indiana University Press.

The company had revenue of about $2 billion in 2012, according to company spokesman Dave McCarty. The maker of needles, catheters and other medical products is valued at $5.8 billion, making Carl Cook the 251st richest person in the world, according to the Bloomberg Billionaires Index. He’s never appeared on an international wealth ranking. The billionaire became chief executive officer of Cook Group upon his father’s death.

“It took us almost fifteen years to transfer the stock to Carl in an equitable way, so the taxes wouldn’t kill the company,” Bill Cook said in the book. “That can happen. You can kill your company by trying to get the stock transferred or to sell it to your children, because of the estate taxes.”

McCarty declined to comment on Carl Cook’s net worth.

Cook Group competes with Minneapolis-based Medtronic Inc., which announced June 16 that it would purchase Dublin, Ireland- based Covidien Plc for $42.9 billion, the largest deal for a medical-device maker in 30 years.

The acquisition, which reflected a 29 percent premium on Covidien’s stock price, highlights a yearlong rally for the industry. Boston Scientific Corp. has outperformed the S&P 500 Index by 16.4 percent in the last twelve months while St. Jude Medical Inc. beat the index by 22 percent during the period.

“It never ends,” Carl Cook said in his father’s biography, referring to the transfer of the company’s shares. “There’s always some other maneuver you have to do, or a ruling comes in and you have to adjust something. But the bulk of what needs to be done is done.”