The 28-year-old’s fortune fell to $14.7 billion Tuesday from $16.2 billion on May 25, as shares of the world’s largest social-networking company dropped 9.6 percent. They slipped another 2.3 percent Wednesday to $28.19. That extended the stock’s losses to 26 percent from the worst-performing large initial public offering in the past decade and cut Zuckerberg’s net worth to $14.4 billion.

“It seems to be a clear reflection that there was just too much stock issued, that the valuation was aggressive and that a lot of people who lined up to buy it really had no intention of holding it,” Jack Ablin, chief investment officer of BMO Harris Private Bank in Chicago, said Tuesday in a telephone interview. The bank oversees about $60 billion of assets.

Facebook shares closed at $38.23 on May 18, the first day they began trading, giving Zuckerberg a net worth of $19.4 billion. The Menlo Park, California-based company ended the day with a price-earnings ratio of 83.1, making it more expensive than 99 percent of Standard & Poor’s 500 Index stocks. The company went public as the equity index was heading for its biggest monthly decline since September.

Facebook options trading began Tuesday, with volume for puts exceeding calls by 1.2 to 1, data compiled by Bloomberg show. More than 200,000 puts were traded Tuesday, giving the holder the right to sell the shares at a specified price. June $30 calls were the most active contracts Wednesday, with volume at 22,896. They were followed by June $28 puts and June $29 puts.