The stock brokerage keeps reporting strong growth and gaining market share.Shares of Interactive Brokers (IBKR 1.99%) popped 16.4% last month, according to data from S&P Global Market Intelligence. The disruptive investment brokerage for sophisticated global traders continues to gain market share and report record profit margins, leading investors to bid up shares to new highs last month. Here's why Interactive Brokers' stock was soaring in January, and whether it is a buy right now. NASDAQ : IBKRInteractiv ...