I contend that the ASTOVL program resulted in McDonnell Douglas being forced to merge with Boeing.
At that time of ASTOVL both P&W’s F119 engine and GE’s F120 engine were in competition also. There were two main propulsion concepts that were submitted. McDonnell Douglas submitted concepts for both gas-coupled lift fan and shaft-coupled lift fan which were both rated as top proposals, while Lockheed submitted a shaft-coupled lift concept. DARPA awarded two contracts, one to McD for the gas-coupled lift system for the F120 and one to Lockheed for the shaft coupled lift fan for the F119. That decision sealed the fate for McD as the F119 was selected to power the JSF and McD was told it would have to include the development cost of the F120 in its JSF cost estimate. As a result McD had to find lower cost alternative lift system and eventually teamed with Northrop who had developed a separate mid-mounted lift engine. The separate engine was considered unacceptable by the Marines.
With the loss of the JSF program, McD was left with no new fighter program and felt it had to merge with Boeing.