TSR, a small company dealing in the fringe hobby of "war gaming" got hugely popular at the beginning of 1980's thanks to an unexpected publicity from a hoax that got propagated by the national media.
The company owners and executives, Gygax and the Bloom brothers were no skilled businessmen and they projected this sudden jump in the company's revenue into the next years, expecting it to grow tenfold in a year. They went on a hiring and acquisition spree accordingly.
As the miraculous growth didn't come, TSR ran into financial problems, running on a $750k deficit by the mid 80's
The Bloom brothers tried to get a big outside investment to get the company out of the red numbers but Gygax opposed - he didn't want non-gamers to control the company. To this effect he executed an ancient option he got when the company was formed, gained a (very narrow) majority of the company's shares and thus the power to strip the Bloom brothers of their executive positions and void the investment by the outsiders.
In response the Blooms wanted to execute the option of selling all their shares back to the company for a large (but not outlandish) sum of some $500K but TSR could not afford it.
Half a year later the Blooms executed the same option Gygax did before to gain a slight majority in the company and sold all of their shares to Lorraine Williams for a third of the price per share, making her the largest and a majority shareholder.
One day later Gygax was stripped of all his executive positions in the company
He fought the decision in court, but really had no case and eventually sold off his shares in order to finance his new business.
How Gygax lost his copyright to D&D and Grayhawk the article does not say
All in all a really boring story