Sept 6 - Investors in the London Stock Exchange Group, including Blackstone and Thomson Reuters , are launching a sale of roughly 28.3 million shares worth about 2.3 billion pounds ($2.9 billion), bookrunners said on Wednesday.

The consortium, which includes Canada's CPPIB and Singapore's GIC, intends to sell a total of about 43.1 million shares over time in the bourse operator.

Thomson Reuters, parent of Reuters News, holds a minority stake in LSEG.

($1 = 0.8002 pounds) (Reporting by Pushkala Aripaka in Bengaluru)