Trades are a common occurrence in sports, but no such major thing has ever happened in the world of Mixed Martial Arts...until now, it seems.

While first discussed on MMAJunkie Radio, ESPN and prominent MMA journalist Ariel Helwani reported the UFC and ONE Championship are close to an agreement that would see the promotions swap two of its respective biggest stars.

The agreement would see former UFC Flyweight Champion Demetrious "Mighty Mouse" Johnson released from his contract to sign with ONE, while former Bellator and ONE Welterweight Champion Ben Askren would be released from his ONE deal to come out of a brief retirement and sign with the UFC.

As MMA fighters are traditionally independent contractors, and both men have fights left on their current deals, the trade must be conducted through this release-and-sign method, rather than an outright exchange.

Social media aftermath

As reported by USA Today's MMAJunkie, with the undefeated Askren now appearing to join the biggest MMA promotion in the world, he has wasted no time going after some of the most well-known UFC fighters in the immediate aftermath of the trade announcement. The fighters he has called out range from Darren Till to the Diaz brothers, and even Conor McGregor.

Askren also has called out UFC Lightweight Champion Khabib Nurmagomedov, feeling that he needs to be humbled in the UFC 229 aftermath [VIDEO].

Askren added that a 165-pound division will come to the UFC; he feels he could be the star to start it up as its face. Askren has traditionally competed at welterweight, which is 170.

A rumor has circulated among the MMA community the 165-pound division could be started with Askren's arrival, but at the expense of the end of the 125-pound flyweight division — thanks to its biggest star and longtime champion, Johnson, being shipped.

Johnson, meanwhile, simply took to Twitter to remove a UFC reference from his handle, and he assured fans he's excited for what the future holds with ONE.

Askren and Johnson

So long as the deal is official, it will represent the end of an era for one of the key figures for smaller fighters in the UFC; while at the same time, bringing the UFC someone considered one of the best to never step foot in its Octagon.

Askren, early in his pro career, won a Bellator MMA welterweight tournament in 2010 before going on to capture the division's title that same year. He'd defend the title four times before leaving the promotion and signing with ONE as a free agent. Askren won the ONE Welterweight Title in 2014 and defended it five times before a retirement stint prior to this trade.

Johnson, after starting his pro career 12-1, debuted for the UFC after World Extreme Cagefighting merged with the UFC at the end of 2010. After back-to-back victories, Johnson fell short in a title shot against then-UFC Bantamweight Champion Dominick Cruz in October 2011.

Johnson then won a UFC Flyweight Title tournament to become the inaugural champion of the division. Johnson would defend the title a record 11 consecutive times before losing the title to Henry Cejudo at UFC 227 this past August. Johnson is only the second man in UFC history to win all possible performance bonuses in his career, was at one time considered the UFC's top pound-for-pound fighter, and won the 2017 Fighter of the Year ESPY.