[7] The company began on March 1, 1945,[1] with a single drugstore along Bambang Street, Santa Cruz, Manila owned by Mariano Que (d. (2017-04-15)April 15, 2017).

[9] The store began cutting packaged, bulk items into single pieces and selling them individually; this retail practice is colloquially called tingí-tingî in Filipino.

[14] Another story claims that Sy was selling footwear in front of Mercury Drug as a sidewalk vendor and then was shooed away by drugstore's security guards.

[14] The story also adds that after years have passed, Mercury Drug had allegedly asked to rent a space at SM malls but was "rejected" and "banned" because Sy had remembered the incident of being driven off by guards.

[14] In 2002, his daughter, Teresita Sy-Coson, wrote The Philippine Star and stated that his father and Mariano Que were "good friends and this friendship extends to family members.

[15] Likewise, Mercury Drug said in an official statement that they have "a high regard for Mr. Henry Sy and the SM Enterprise" and they "respect each other's business endeavors and maintain a friendly attitude toward each other.

President Benigno Aquino III considered hamburgers his comfort food and usually visited its branch at Jaka Plaza along Sucat Road in Parañaque as it was his favorite restaurant.