Market Data 
By Arathy Somasekhar
HOUSTON (Reuters) -Autry Stephens, the billionaire founder and chairman of Endeavor Energy Resources, has died aged 86, the company disclosed on Friday, after a prolonged battle with cancer.
Stephens died early on Friday morning, a source familiar with the matter said.
Known for a relentless work ethic and frugal nature, he had continued to work while under medical care and relied on friends to fly him in a private jet to cancer treatments in Houston.
His work ethic was shaped by tough years in the 1980s and 1990s when he struggled to get Endeavor off the ground, sources said. The wildcatter launched Endeavor in 1979 and grew it into one of the largest closely held U.S. oil and gas firms by buying tough-to-drill wells that oil majors snubbed.
Stephens in February agreed to sell his Midland, Texas-based company for $26 billion to local rival Diamondback (NASDAQ:) Energy. He had rebuffed many offers for the business over the years. The deal is expected to close later this year.
Stephens’ daughter, Lyndal Greth, becomes chairman of Endeavor’s board of managers, the company said on Friday. Greth was previously vice chairman.
Born in 1938, Stephens grew up on a farm in DeLeon, Texas, where his family grew peanuts and fruits. He studied engineering and went to work for Humble Oil & Refining, a predecessor to Exxon Mobil (NYSE:), according to a profile on the University of Texas’ engineering school website.
Stephens drilled his first well in 1979 in Midland county, Texas. He would pick up leaseholds for acreage that oil majors found too expensive to drill and would lower production costs by handling most of the operations. He created and used his own fracking, construction and trucking companies.
Stephens was well known in Midland, Texas, the heart of the U.S. shale business, and for bringing his dog to his office regularly. He named one of his companies Big Dog Drilling.
“He was stubborn and persistent. And in the right place at the right time,” said Javaid Anwar, a Texas businessman who first met Stephens 1976 while working at a bank in Midland.
The two became friends in the years that followed through numerous fishing trips and business deals.
“He was a fish hog,” joked Anwar, recounting how Stephens used to take up his coveted turns to reel in catch on their fishing trips.
Anwar helped fly Stephens to Houston on his private jet for cancer treatments over the past year, which gave the two the opportunity to look back at old memories from their time in the oil business.
“He was one of the pioneers of horizontal drilling that helped the Permian come to produce nearly 6.5 million barrels of oil per day, roughly half of the U.S. total,” Anwar said.
