全句結構：
狀語：In addition to Zuckerberg and Moskovitz, the world's youngest billionaires,
主語：pledges
謂語：were made
狀語：by AOL co-founder Steve Case, financier Carl Icahn and Michael Milken, a former Wall Street executive
這個executive的定語從句：who went to prison in the early 1990s for securities violations.