Formed 1954 as a specialist maintenance and modification contractor for Douglas B-26 Invader bombers, developing high-speed executive transport and heavily armed counterinsurgency versions. The On Mark Marketeer was a six/eight-seat corporate transport based on the B-26 airframe. The externally similar Marksman had a pressurized cabin. A B-26K Counter Invader was developed for the USAF's Tactical Air Command.
In 1962 Mark was responsible for the first Pregnant Guppy conversions of the Boeing Stratocruiser, on behalf of Aero Spacelines Inc, for the transportation of space rockets and other bulky cargo.
At about the time Grumman was casting the Gulfstream in stone, there was a meeting at On Mark to decide upon a new airplane, a turboprop of original design. Although its ulti-mate price would have been equal to or less than the Gulfstream's first tag of roughly $800,000, the directors of On Mark decided that nobody would pay such a price for a bus-iness airplane. And the company died.