It was ingenious and audacious, and officials at the Internal Revenue Service were upset.

In November 2006 Fortress Investment Group LLC filed its first documents with the Securities and Exchange Commission in advance of going public. Fortress is a fabulously profitable investment vehicle that is part hedge fund and part private equity firm, with roughly $43 billion in assets under management. Most major companies cleverly structure transactions to reduce taxes, but Fortress’ efforts — crafted by Skadden, Arps, Slate, Meagher & Flom — were Olympian. Through a dazzlingly complex structure, it managed to avoid nearly all corporate tax and steer clear of SEC scrutiny of its investments.