Cofounder of financial news and data juggernaut Bloomberg LP debuts on The Forbes 400 after partner, New York City Mayor Michael Bloomberg, bought back 20% stake in the firm from Merrill Lynch for $4.5 billion this summer. Company now worth more than $22 billion; owns 4% stake. Studied math at SUNY Binghamton; took job in systems research at Salomon Brothers. Traded bonds at Morgan Stanley; joined Michael Bloomberg and others to launch financial information services firm Innovative Market Systems 1982. Later renamed Bloomberg LP. Pitched Merrill Lynch on prototype that could crunch financial data, provide information on government bonds 1983; sold Merrill a 30% stake for $30 million. Today Secunda oversees all Bloomberg financial products.