TradeStation Group Inc. (Nasdaq: TRAD) stock rose 30.5% to $9.67, after Japanese online brokerage Monex Group Inc. said it would acquire the Florida-based platform operator for about $411 million.

Volume for TradeStation had topped 18 million shares by late morning Thursday, overwhelming its daily average of 236,000, as the price charged near its previous 52-week high of $9.70.

Under the terms of the agreement, which has been unanimously approved by TradeStation and Monex’s respective Boards of Directors, TradeStation’s shareholders will receive $9.75 in cash for each outstanding share of TradeStation common stock they own, which represents a 39% premium to TradeStation’s share price on March 21, and a 32% premium to TradeStation’s closing stock price on April 20, the last full trading day before today’s announcement.

“We are pleased to announce this transaction, as it delivers significant value to our shareholders,” said TradeStation Chairman/CEO Salomon Sredni. “Monex is a leader in Japan’s online brokerage market, and we believe it will be a great partner as we go forward as part of the Monex family.”

TradeStation is an electronic trading platform that offers state-of-the-art electronic order placement and execution and enables clients to scan the markets and design, test, optimize, monitor and automate their own custom Equities, Options, Futures and Forex trading strategies.