We've all seen VCs bet big on multiple startups in the same sector, but that "diversification" can get tricky when those companies start fighting for the same customers. That's exactly why the US Department of Justice (DOJ) has spent the last year investigating a16z. Using a 112-year-old antitrust law, the DOJ is looking into how the firm manages its board seats—specifically since Ben Horowitz sits on the board of Databricks while Martin Casado is with Fivetran, two companies that are now direct competitors.

While these startups weren't rivals when a16z first invested, their growth eventually led to overlapping business areas. Now, the DOJ wants to see how VCs handle these blurred lines to ensure fair competition. It's a wake-up call that even the biggest players in Silicon Valley still have to play by the old-school rules of the game.