Japanese telecoms firm SoftBank Corp has pumped in $250 million to become the top investor in Southeast Asian mobile taxi-booking application GrabTaxi Holdings Pte Ltd, its biggest investment in a Southeast Asian Internet firm. GrabTaxi, which allows customers to order cabs closest to their location by mobile phone, operates in Singapore, Malaysia, Thailand, Vietnam, Indonesia and the Philippines. In a statement, the two companies said the funding will be used to accelerate the app’s expansion in the region. The investment in GrabTaxi comes about a month after SoftBank and its billionaire CEO and founder Masayoshi Son announced a $627 million funding into online marketplace Snapdeal as part of a plan to put $10 billion into India’s booming online retail market. The Japanese firm is the largest investor in recently listed Chinese e-commerce giant Alibaba Group Holding Ltd. Taxi-hailing apps have become popular in Southeast Asia, especially Singapore, one of the most expensive places in the world to own a private car.