The hedge fund claims Grayscale refuses to redeem shares because doing so would cut into profits.
Bridgewater founder Ray Dalio in October relinquished control of the firm that now manages about $150 billion.
Even the masters of the universe have trouble keeping up with the random walk of financial markets.
The billionaire investor has turned to professional baseball and is pressing his advantage by spending big to win.
He also thinks markets will stagnate for the next decade.
The firm was one of the early investors in Twitter, Facebook and Airbnb.
Anthony Scaramucci made a big push into crypto, a move that has hurt Skybridge's performance this year.
The Finra award is likely among the biggest seen in years inside Wall Street's secretive arbitration system.
Gabe Plotkin abruptly announced in May that he's winding down Melvin Capital Management.
Of the 42 stocks owned by at least half of the Tiger Cubs at the end of December, all but two are down for the year.