As reported by The Times, the UK bookmaker has emerged as a key contender to buy the spread betting group for up to £70 million.
Duke Street Capital, the private equity owner of Sporting Index which originally asked a price closer to £100 million, set next week as the deadline for bidders to table their second-round offers.
Ladbrokes appears to have an advantage over private equity rivals by being able to cross-sell its own betting products to Sporting Index punters while offering Sporting Index to its customers.
The bookmaker, which abandoned a spread-betting foray in the 1990s, recently joined forces with rival spread firm Cantor Index to launch Ladbrokes Financials which offers fixed odd bets on the movement of the FTSE and Dow Jones markets.