TORONTO – John Thornton, an ex-investment banker at the center of a wave of consolidation in the gold space, has just put his largest rival on the defensive.

Thornton is executive chairman at Barrick Gold Corp, the world’s second-largest gold producer. On Friday, Barrick confirmed it is considering merging with Newmont Mining Corp, the biggest producer, in an all-share zero premium deal that would be the largest ever pulled off in the gold mining industry.

While Barrick said no decision has been made, such a deal would serve as an enormous victory for Thornton, an ex- Goldman Sachs banker whose appointment to the top Barrick position in 2014 without mining experience was viewed skeptically within the tight-knit Canadian mining community.

Newmont and Barrick have danced with each other regularly over the years, at the corporate and asset level. Merger talks between the two fell apart in the 11th hour in 2014, and since then the two companies have struggled even to find common ground on asset sales, such as their jointly owned super pit mine in Australia. While Barrick is willing to sell its stake in the project, Newmont hasn’t been able to strike a deal.

Barrick’s late founder, Peter Munk, a staunch Canadian patriot, was against the idea of Colorado-based Newmont taking over the Toronto-based miner. That threat was discussed internally at Barrick last year, and was a driving force behind its $5.4 billion merger with Randgold Resources, according to people familiar with the matter, who asked not to be named because the discussions were private. That agreement, completed in January, was partly driven by the need to fortify Barrick’s position, the people said.

The Randgold-Barrick merger, in turn, may have pushed Newmont into its own defensive play. News last month that it planned to acquire Vancouver-based Goldcorp Inc. in a $10-billion mega-merger didn’t impress Newmont shareholders, but viewing it as a defensive strategy adds another dimension to the buy.

It also explains why Barrick may feel compelled to act soon. If Newmont merges with Goldcorp, it becomes a much bigger mouthful for the Toronto miner to bite off. Even before the acquisition is completed, Newmont has already vaulted ahead of Barrick to become the largest gold producer.

The lone wolf stranded in all of this is, of course Goldcorp. If Barrick gobbles up Newmont, Goldcorp could be left vulnerable. Newmont proxy materials indicate its own takeover play for Goldcorp was sped up by fears of a bid from another rival, widely thought to be Newcrest Mining Ltd.

If Newmont-Goldcorp falls apart, the question would be where Newcrest fits into the Barrick-Newmont play, if at all. If it were to be involved in the mega-deal, the question would be which mid-tier gold companies are left scrambling for Goldcorp assets.