British American Tobacco p.l.c. (LSE:BATS) is preparing to kick off a sale of part of its stake in Indian partner ITC Limited (NSEI:ITC) as soon as this week, people with knowledge of the matter said. London-listed BAT has been speaking with Bank of America Corp. and Citigroup Inc. about a potential divestment of around $2 billion to $3 billion in ITC stock through block trades, the people said.