The move appears to alleviate concerns that National Amusements could lose control of the companies or run into trouble with its creditors.
The company said the move will allow it to retain controlling interests in both CBS and Viacom while paying off its own borrowings in full. It said it will still have 75 percent voting control in each company and does not plan to reduce its stake any further.
Dedham, Mass.-based National Amusements expects to raise $600 million selling shares of Viacom, which includes the Paramount movie studio as well as cable networks MTV and Comedy Central, and $345 million from CBS shares.
The company, which also owns a chain of movie theaters in the U.S., U.K., Latin America and Russia, restructured $1.46 billion of borrowings in May, pushing the debt's maturity to Dec. 31, 2010 with certain payments due this year and next.
It has been looking to sell some 600 of its movie screens in the U.S. to help raise cash. The company said Wednesday the sale of Viacom and CBS stock will allow it to hold on to its "core" U.S. theater properties.
"As a result of our actions, National Amusements will be out of debt with its existing creditors and will still control its most important assets," Redstone said in a statement.