Singapore's state-owned investment firms Temasek Holdings Pte and GIC Pte, long-term Alibaba Group Holding Ltd investors, bought a combined $1 billion stake in the Chinese e-commerce behemoth, the second-biggest stakes being sold by SoftBank Group Corp.

The purchases add to the technology holdings of both investment firms.

Temasek and GIC were early investors in Alibaba and hold major stakes in technology firms benefiting from the economic growth of the world's second-biggest economy.