HONG KONG, Feb 5 (Reuters) - Alibaba Group Holdings said it had raised $5 billion as it finalised its mega U.S. dollar bond deal on Friday, as investors overlooked the company’s ongoing regulatory scrutiny in China. Pricing was set tighter than initially flagged by the company when its initial price guidance was published on Thursday, indicating strong demand to buy the e-commerce giant’s debt despite an anti-trust investigation into the company. The $5 billion was raised in four tranches of 10-, 20-, 30- and 40-year debt. (Reporting by Scott Murdoch in Hong Kong; Editing by Lincoln Feast.)