The Delta II is a rocket capable of up to 6 metric tons to LEO, and has the best safety record of any launcher in history. ULA still has the launcher listed as one of its products because it has one unsold rocket, but it has stopped making them, despite the rocket's great success. From SpaceFlightNow:
The United Launch Alliance vehicle has flown 153 times since 1989, accumulating 151 successes and currently rides a string of 98 consecutive flawless missions. Only three vehicles remain in inventory, with NASA the customer for two of them to launch the JPSS 1 weather satellite in 2016 and the ICESat 2 environmental spacecraft in 2017, both from Vandenberg Air Force Base in California. That leaves one rocket up for grabs, but no one appears to have a payload in the class range of the Delta 2 from the sole remaining launch site to polar orbit interested in purchasing the ride. “I’m afraid, no, I don’t have a sale for it,” said ULA CEO and President Tory Bruno. “We are keeping it in the factory for now in case somebody appears or we need a spare part for the last two birds that are sold.”
SpaceFlightNow also has an article explaining that the Taurus 2 and Falcon 9 have out-competed the Delta II on price:
Both rockets are designed to be less expensive than current launchers, an important factor for science missions in a tight budget environment. Lower launch costs would allow more missions to be started for less money.
Alright, but is ULA really not going to put up a fight somehow? Is there really no other market for them for the world's most reliable rocket? Is there some strategic reason why they aren't interested in cutting the price for the sake of maintaining a market share?