** China-based robotaxi firm Pony AI jumps over 15% to $15 in market debut
** American depositary shares open at $15 vs IPO price of $13, giving the company a valuation of $5.25 billion
** Pony AI sold 20 million ADS in the IPO priced at $13 each to raise $260 million
** Company also raised an additional $153.4 million in concurrent private placement
** Toyota Motor-backed company's valuation has come down from $8.5 billion two years ago
** Pony AI remains unprofitable as it invests in expanding operations
(Reporting by Pritam Biswas in Bengaluru)
((Pritam.Biswas@thomsonreuters.com))