The past three years have seen Sovereign Wealth Funds (SWF) capturing headlines for high-profile investments in innovative technology businesses. The Public Investment Fund of Saudi Arabia may have made the most noise in 2016 with its attention-grabbing $3.5 billion Uber stake and, more recently, a collaboration with Softbank on a "$100 billion" tech-focused venture capital fund. Yet such announcements are merely the tip of the iceberg.