SOFIA (Bulgaria), December 7 (SeeNews) - Cellulose producer Svilosa [BUL:3MZ] saw its share price rise most among all companies listed on the Bulgarian Stock Exchange on Friday, by 5.88%, after the country's financial regulator allowed the publication of an improved buyout offer by A.R.U.S. Holding for the 6.47% stake in Svilosa it does not currently own.