Explore the intricacies of over-the-counter financial markets in this 57-minute conference talk by Darrell Duffie, presented at the "Panorama of Mathematics" event organized by the Hausdorff Center for Mathematics. Delve into the concept of price transparency, examining its implications for various financial markets, including the Federal Funds Market. Gain insights into the challenges of contacting investors, the role of uncertainty, and the application of stochastic processes in financial modeling. Investigate real-world examples, including benchmark manipulation and the diamond paradox. Conclude with a discussion on emerging topics such as dark pools and their impact on market dynamics.