Mark Zuckerberg’s big sister is moving on from her six-year career with Facebook to start up her own business, according to media reports.

Randi Zuckerberg, 29, who served as director of marketing at Facebook and is also the sister of CEO and co-founder Mark Zuckerberg, is parting company after six years to launch a new social media firm.

Her official resignation letter, which was published by All Things D, says *now* is an ideal time for her to build a new company focused on social media.

“I have spent my years at Facebook pouring my heart and soul into innovating and pushing the media industry forward by introducing new concepts around live, social, participatory viewing that the media industry has since adopted. We have made incredible progress, but there is still much to be done and other ways I can affect change. Now is the perfect time for me to move outside of Facebook to build a company focused on the exciting trends underway in the media industry,” the letter said.

The company, which is called R to Z Media, appears to be in its infancy based on a message posted on the home page of the R to Z company website:  ”In true start-up spirit, we’re still working on absolutely everything about this new initiative. Many more details to come.”

According to Business Insider, Randi Zuckerberg had been out on maternity leave for the past few months; time “she likely used the time away to reflect on her own goals,” the report said.

Among her many talents, it appears the elder Zuckerberg can also sing. Check out this video of Randi belting out “Summertime” at the DLD Chairman’s Dinner in Munich in January 2011.

And while her brother Mark might be a social media genius, it seems his style may not be so “smart.” 

The men’s lifestyle and fashion magazine GQ ranked the 15 worst-dressed men in Silicon Valley, and the poster boy for the jeans-wearing executive, Mark Zuckerberg, took the top spot.

However, in this TechZone360 report, Beecher Tuttle defends the younger Zuckerberg: “Judging simply by the photos used for the article, Zuckerberg has no business being ranked at the top of the list.”

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