* Offer to by Six's stakes in JVs for 650 mln francs
* Six owns 49.1 pct of Stoxx, 50.1 pct of Indexium
* Equity indices business booming on ETF interest (Adds source comment, context, detail)
FRANKFURT, June 29 (Reuters) - Deutsche Boerse isin talks with Swiss Six Group to buy the remaining stakes intheir equity index joint ventures Stoxx and Indexium for 650million Swiss francs ($692 million), the two exchange operatorssaid on Monday.
People familiar with the situation said Deutsche Boerse onlyrecently approached Six with the acquisition prospect.
Six does not see global indices as necessarily part of itscore business but it remains open whether the two exchanges willcome to an agreement over the sale, the people added.
Exchange operators have been keen to buy equity indexbusiness to boost revenue as the trend for large investors totrack indices through, for example, Exchange Traded Funds (ETFs)rather than making choices on individual stocks has grown.
Deutsche Boerse owns 50.1 percent of Stoxx AG and 49.9percent of Indexium AG.
"The parties want to clarify all other contractualmodalities in the upcoming negotiations," Deutsche Boerse saidin a statement.
A successful conclusion would be the first for DeutscheBoerse's new Chief Executive Carsten Kengeter, who has said hewould not rule out either bolt-on or large acquisitions as theexchange operator reviews its business targets and prospects.
The London Stock Exchange last year bought U.S.indices group Frank Russell for $2.7 billion, in a move aimed atputting it into third position in ETFs behind global marketleaders S&P Dow Jones and MSCI.
The German exchange operator also looked at the indexbusiness that Barclays Plc put up for auction butdecided not to pursue it, people familiar with the situationsaid.
($1 = 0.9390 Swiss francs) (Reporting by Jonathan Gould and Andreas Kroener; Editing byGeorgina Prodhan)