A 75-Year-Old Granny Is One Of Square's Most Trusted Advisors

Natalie Yellin, 75, has been a long time user of Square. Square is a mobile payment company co-founded by Jack Dorsey which is eying an IPO in 2014.

Yellin first tested Square when she sent her grandson, Brian Grassadonia, $50 for his birthday. Grassadonia was one of Square's first employees.

Before long, Yellin became a household name in the Twitter office. Most of Grassadonia's colleagues follow her on the social network, including its co-founder Jack Dorsey. Wall Street Journal's Katherine Rosman has the story.

Grassadonia's Twitter co-workers first noticed his grandmother when she tweeted at him in frustration in 2011. She wanted him to return her phone call about a vacation to the Grand Canyon and added @square to the tweet.

The tweet showed up on large monitors around Square's office. Grassadonia's colleagues had a field day with it and sent a company-wide email asking him to call his grandmother.

"Everyone started following her-everyone," Grassadonia tells Rosman. "People started walking up to me every day to say, 'I just talked to your grandmother, she's doing great.' "

Yellin has even helped Square hire. She recommended one of its key employees, Square's merchant outreach coordinator.

While Yellin joined Twitter to get in touch with her grandson, she's taken to the social network. She has now sent more than 13,000 tweets from her handle, @GrannyNY. Her bio sums it all up: "Travel enthusiast, @Square fan, started on twitter to get in touch with my workaholic grandson, Brian @Grassadonia ...got his coworkers and @jack instead."