IT WAS MEANT TO BE ANIL AMBANl'S big DAY in MORE ways than ONE. ON February 11, Reliance Power, which had just wrapped up India's biggest ipo ever and the first from Ambani's Reliance-Anil Dhirubhai Ambani Group, was to list on the Bombay Stock Exchange. As much as the investors in the Rs 11,500-crore ipo, which was oversubscribed 73 times, Ambani must have been anxious. If the Reliance Power stock closed at Rs 500 against the offer price of Rs 450 (Rs 430 for retail investors), it would not just add Rs 1,13,000 crore to r-adag's market value but also make the 48-year-old Ambani the richest Indian, ahead of his brother and Reliance Industries supremo Mukesh Ambani and steel czar Lakshmi Niwas Mittal. Alas, that was not to be. Within minutes of Ambani ringing the ceremonial bell at bse, the stock began to soar (it touched a high of Rs 599.90) but only to slip later. By the end of the day, it was at Rs 372.50