IF TIDJANE THIAM, UK insurer Prudential’s chief executive, manages to buy the highly prized AIA, it will be something of a miracle. As part of AIG’s plan to pay back the $180 billion of US taxpayer money that it had to borrow during the crisis, the firm has been considering the sale or IPO of its Asian life insurance unit, AIA, which has $60 billion in assets under management and is regarded as AIG’s "jewel in the crown". In February, Prudential stepped forward – the only competitor willing to pay the $35.5 billion that AIG was demanding for the Hong Kong business. However, UK regulator the Financial Services Authority (FSA) was unimpressed. After hacking it out with Prudential about whether the firm was putting itself at risk by making the purchase, the regulator finally relented. To meet the FSA’s requirements, Prudential had to switch some $5.5 billion in cheaper senior debt into $5.4