Visa's investment in Square represents about 1 percent stake

Visa told Reuters its current holdings are just more than 4.19 million shares of Class B common stock.

The company has the option to convert up to 3.52 million of these shares into Class A stock, according to a disclosure filed with the Securities and Exchange Commission on Thursday, which would give it at most a 9.99 percent stake in the share class.

If other shareholders also choose to convert their stock at the same time Visa's stake would be less.

Square, run by Jack Dorsey, who is also chief executive of Twitter Inc , held an initial public offering in November.

Visa's about 1 percent stake is based on Square's fully diluted common equity as of Dec. 31, 2015.

(Reporting by Heather Somerville; Editing by Bernard Orr)