Hedge fund manager Ken Griffin continued to sell Tesla in the second quarter, but he bought a substantial position in Nvidia.Ken Griffin of Citadel Advisors is the most successful hedge fund manager in U.S. history as measured by net gains. Further, Citadel beat the S&P 500 (^GSPC 0.49%) by 9 percentage points during the last three years, which makes his portfolio a good place for individual investors to find inspiration.Griffin made several noteworthy trades during the second quarter. He sold shares of Tes ...