BERLIN, June 8 (Reuters) - Online brokerage Scalable Capital said on Tuesday it had raised 150 million euros ($183 million) from investors led by China's Tencent, becoming the latest German fintech to attract sizable funding.

The funding round, backed by existing investors including fund manager BlackRock Inc, values Scalable Capital at $1.4 billion and comes on the heels of a $900 million raise by rival online broker Trade Republic.

Scalable will invest the proceeds in developing its brokerage and wealth management businesses as it sets its sights on becoming Europe's leading online investment platform, its co-CEO and co-founder, Erik Podzuweit, told Reuters.

Active since 2016, Scalable has more than $5 billion in assets under management with its robo-adviser offering of exchange-traded funds for investors and flat-rate subscriptions of 2.99 euros a month for day traders.

Podzuweit said that bringing on board Tencent, which has also backed Berlin-based e-bank N26 and Nasdaq-listed Chinese neo-broker Futu, would help Scalable to strengthen its appeal for millennials who invest via their smartphones.

"For us, the interest is the expertise they bring in the mobile area," said Podzuweit, a Goldman Sachs alumnus like his fellow founders Florian Prucker and Adam French.

Scalable, which is present in Germany and Austria, will invest the proceeds from the Series E round in launching in France, Italy and Spain, as well as looking to add cryptocurrencies to its range of brokerage products.

Headquartered in Munich and with an office in London, Scalable is opening a new location in Berlin as it seeks to strengthen its engineering and marketing teams. It expects its workforce to more than double this year to 400, said Podzuweit. ($1 = 0.8212 euros) (Writing by Douglas Busvine. Editing by Jane Merriman)