Frasers, which owns Sports Direct, plans to spend up to £80m buying back its stock.
This has pushed up its share price by 2.7% to 790p.
This could help Frasers hold onto its spot in the blue-chip index.
It is currently the smallest company on the FTSE 100, putting it at risk of demotion to the smaller FTSE 250 index when the quarterly reshuffle is calculated next week.
According to Proactive Investors: “As the month of March comes into view it brings the first FTSE 100 and 250 index reshuffles of the year, with Mike Ashley’s Frasers Group PLC teetering on the edge of relegation.”