Retail trading platform Robinhood Markets will acquire portfolio management platform TradePMR in a cash-and-stock deal for about $300 million, the companies said on Tuesday. Robinhood has been pushing to grab market share from traditional brokerages such as Charles Schwab and Fidelity Investments in its effort to become to a full-fledged financial services provider. Over the past few months, Robinhood has unveiled a credit card, launched a desktop trading platform, added futures and index