SINGAPORE, Sept 1 (Reuters) - Singapore Exchange is preparing to roll out easier guidelines for listings of special purpose acquisition companies (SPACs) in the city-state, which would make it the first major Asian bourse to accept such investment vehicles, four sources familiar with the matter told Reuters on Wednesday. The changes come after SGX (SGXL.SI) , which has struggled to capture large listings of high-growth companies, received market feedback that some of its earlier proposals were too strict. SGX"s regulatory arm is now considering easing a minimum S$300 million ($223.2 million) market value proposal for SPACs and a proposal that warrants cannot be detached from underlying shares, two of the sources said. The sources declined to be identified as they were not authorised to speak about the matter. SGX faces prospects of losing out in courting Southeast Asian startups looking to list in their home markets or in the United States. "We are carefully reviewing the feedback and carrying out our engagements with respondents, regulators and other stakeholders," a SGX spokesperson said in an email to Reuters. SGX said that given the high level of interest, it is looking to publish the results of its consultation "as soon as possible." SPACs are shell corporations that list on stock exchanges and then merge with an existing company to take that public, offering it shorter listing timeframes and strong valuations. Though SGX will have an early mover advantage, one lawyer said it would still be challenging for it to become a vibrant platform for SPACs. "Whether SPACs will take pride of place in the Singapore market, like real estate investment trusts, will depend on whether there is a perceptible track record of good valuations and liquidity post-SPAC mergers," said Robson Lee, a partner at Gibson, Dunn & Crutcher LLP. In a consultation paper for SPAC listings issued in late March, SGX had outlined measures to rein in risks seen in U.S. SPACs such as excessive dilution by shareholders and sponsors and a rush by these firms to merge with targets. All the sources Reuters spoke to said that SGX was likely to introduce other measures to safeguard investor interests but would simplify proposed guidelines to still make it attractive for SPACs. In other markets, Hong Kong and Indonesia are taking tentative steps for the potential listing of SPACs, while Britain has eased rules. But such investment vehicles are peaking in popularity in the United States as regulators there clamp down on SPACs after a listing frenzy. Hamstrung by a small base of retail investors, SGX has grappled with low liquidity and valuations. However, over the past few years, it has built up a lucrative Asian derivatives business and still remains a global listing venue for real estate investment trusts. IPO fundraisings on SGX from January to late August fell to a six-year low of $239 million in Southeast Asia"s total tally of about $8.4 billion, placing Singapore behind Malaysia, Philippines, Indonesia, and Thailand, according to data from Refinitiv ($1 = 1.3441 Singapore dollars)