Ann: Ceasing to be a substantial holder from MS, page-49

It is a possibility in order for them to get their hands on Cavatak at a discount special.
However there would need to be a lot of trust between the two parties. If they think this product will be key for their future they certainly would want to be in control of it rather than relying on the competition to stick to some agreement made. It would be easy for the other party later on changing their mind (yes might result in legal battle) to hinder opponents success and get in pole position....