The mobile payments firm is now valued at $6bn.
Mobile payments startup Square has reportedly raised $150m at a $6bn valuation led by the Government of Singapore Investment Corporation.
According to The New York Times, the closed funding round was also led by existing investors Goldman Sachs and Rizvi Traverse Management among others.
"We stand for independent businesses and will continue to invest aggressively to empower them with tools that help them grow," a Square spokesman said.
The funding comes after a filing in September disclosed that Square had planned to raise at least $100m in a then-unclosed round. In August, rumours also surfaced that the firm was trying to raise $200m, which included funding from the Government of Singapore Investment Corporation.
Square, which was founded in 2009 by Twitter co-founder Jack Dorsey, offers businesses a detachable card reader which lets smartphones process credit and debit card payments
It has proved to be a significant success since its launch, attracting a range of competitors, including Amazon’s Local Register, a $10 rival service from the ecommerce giant earlier this month targeting small businesses.
Square, which competes against Paypal, Google Wallet and Limpman among others, also launched Square Capital, a cash advance programme for small businesses, in May.