Aug 5 (Reuters) - Uber Technologies forecast current-quarter adjusted earnings below Wall Street estimates on Wednesday, saying that foreign exchange would trim bookings growth and reaffirming plans to invest heavily in robotaxis and acquisitions. The global ride-hailing and delivery giant’s capital allocation has become a key investor focus after it announced a US$14.8-billion deal for Delivery Hero DHER.DE last month, which it plans to fund with existing liquidity and debt. The company on Wednesday also outlined plans to spend more than US$10 billion on autonomous vehicles over the coming years, but did not provide a specific timeline. Shares fell about 3 per cent in premarket trading. It forecast third-quarter gross bookings of US$58.25 billion to US$60.25 billion, broadly in line with analysts’ expectations of US$59.21 billion, according to data compiled by LSEG. Foreign exchange is expected to trim reported third-quarter gross bookings growth by about one percentage point from last year, the company said, after boosting growth over the previous four quarters. Uber’s second-quarter gross bookings of US$58.02 billion topped analysts’ estimates of US$57.06 billion, while adjusted core earnings also exceeded expectations. The business benefited from broad-based demand across regions and services during the quarter, including travel linked to the FIFA World Cup, Uber CEO Dara Khosrowshahi said. More than 8 million tourists used Uber in host cities during the tournament, according to the company. Revenue rose 12 per cent to US$14.19 billion, narrowly missing estimates of US$14.24 billion after an accounting change in Britain reduced reported sales growth without affecting the underlying economics. It forecast adjusted earnings per share of 84 cents to 88 cents, compared with analysts’ expectations of 89 cents, according to data compiled by LSEG. Operating expenses rose about 10 per cent in the second quarter, with spending increasing across marketing, research and administrative operations. Uber said it added more first-time users over the past year than during any comparable period in the previous five years, helping lift gross bookings by 24 per cent. (Reporting by Akash Sriram in Bengaluru; Editing by Leroy Leo)