Back in May of 2011 Nikon filed a patent infringement lawsuit against Sigma over lenses with VR technology. I was told that the negotiations between the two companies should be finalized in the coming weeks and a press release will be issued. Nikon was initially looking for a compensation of 12.6 billion yen (around 150 million dollars) which I assume is a lot of money for Sigma. I am not sure of the final outcome, or least not confident enough to post it online.
