(Reuters) - Instacart has more than doubled its valuation in less than six months to $39 billion with a $265 million fundraising round from existing investors, as the grocery delivery company benefits from a surge in online orders during the COVID-19 pandemic. The San Francisco start-up, whose transaction volumes surged sixfold last year as doorstep delivery boomed during lockdowns, said on Tuesday it plans to use part of the new funds to increase its corporate headcount by an estimated 50% in 2021. The company was valued at $17.8 billion in November following the closing of a previous funding round. That same month, Reuters reported Instacart had picked Goldman Sachs Group Inc to lead its initial public offering at around a $30 billion valuation. Its latest cash injection comes just a few months after California backed a ballot proposal that upheld the status of app-based delivery drivers as independent contractors- a major boost for the likes of Instacart and Uber Technologies Inc, which rely on people to work independently and not as employees. The new funding round was led by Andreessen Horowitz, Sequoia Capital, D1 Capital Partners, Fidelity Management & Research Co and T. Rowe Price Associates.