Mark Zuckerberg, Facebook founder, plans to sell shares in his company worth about US$2.3 billion.
The sale of 41.4 million shares will reduce his voting power in the company from almost 60% to 56%.
Facebook says Mr. Zuckerberg will use money raised from the share sale to pay a tax bill, related to another share transaction.
Mr. Zuckerberg's sale is part of a bigger offering by the company of 70 million new shares.
Facebook first sold shares on the stock exchange in May 2012, priced at US$38 each.
They are now trading at about US$55, a rise of almost 45%.
Investors have been encouraged by strong results.