The world's biggest prescription drugmaker started building up the stake - worth 33 percent of Roche's voting shares - as a basis for a possible merger more than a decade ago, but the plan never materialized.
Novartis plans to sell the stake in a so-called order book process, having banks collect purchase offers within a predefined price range from selected investors, weekly Sonntagszeitung said, citing board and banking sources. A Novartis spokesman declined to comment on the report. (Reporting by Kirsti Knolle; Editing by Alison Williams)