Patents for mobile technology have been receding somewhat from the sky-high values seen earlier amid intense litigation and legal developments may be among the reasons [Ina Fried, Re/Code]:
Over the past couple of years, more patents are being overturned as part of a more extensive post-grant review process at the patent office. Various court rulings have also made it harder to get injunctions on standards-essential patents. Finally, the Supreme Court set new limits in a key case over software patents, known as the Alice decision.
More on Alice v. CLS Bank here.