Aflac (NYSE:AFL) stock is on the rise today as a Japan courier conglomerate has made a sizable investment on the insurance company.

Japan Post said that it will be placing a bet of approximately $2.6 billion on the Columbus, Georgia-based insurer, which will make it the largest Aflac shareholder in the country. The deal will allow Japan Post to increase its stake to a maximum of about 20% in four years from now.

The current largest shareholder of the insurance giant is Vanguard Group, which has an 8.8% stake on the company, according to data compiled by Refinitiv. Aflac told Reuters that the company was in talks with Japan Post over the latter becoming a minority stake owner on the former. However, the deal did not say anything regarding Aflac or any of its subsidiaries becoming part of Japan Post.

The deal has not been made official by either party yet in a public setting, but it is expected to be unveiled sometime later this month. Reuters added that Aflac did not comment any further on the matter, while a spokesman for Japan Post did not have anything to say on the matter either.

The agreement is a follow-up of an announcement made five years ago, allowing Aflac to sell its cancer insurance at Japan Post’s offices across Japan.

AFL stock is up close to 6% on Thursday following the investment news.