Stifel Financial Corp. announced Monday it will buy rival Thomas Weisel Partners Group Inc., as part of Stifel’s continuing effort to expand its investment banking and capital markets businesses.

The deal, which is expected to close on or around June 30, is valued at over $300 million in stock. The price also includes restricted stock and warrants that Thomas Weisel will receive.

As part of the deal, each Thomas Weisel share will be exchanged for 0.1364 shares of Stifel common stock. Thomas Weisel has approximately 32.8 million shares outstanding as of March 31. Based on Stifel's Friday close of $55.74, the deal offers a premium of 74%.

Estimated annual revenues for the combined company are approximately $1.6 billion.

“Stifel Financial purchase of Thomas Weisel Partners represents a meaningful consolidation of brokerage power outside the traditional wirehouse brokerage and investment banking segments, as both firms have a strong industry presence,” said Aite Group senior analyst Doug Dannemiller. “In terms of market segment shifts, Stifel’s segment, self-clearing independent brokerage, has been winning share within wealth management for the past two years. As the effect of the financial crisis wears off, traditional competition, based on service, price, and product offering will drive success. This move is well timed to position Stifel for the next phase of competition.”

Stifel said the merger will boost its investment banking, research and wealth management capabilities.

“We expect the combined firm to benefit from the investment banking, research, and sales and trading platforms of both firms, as well as the brokerage services offered by Stifel's Global Wealth Management Division and the strong venture capital relationships and expertise in growth companies of Thomas Weisel Partners,” Ronald J. Kruszewski, Stifel’s chairman, president and chief executive officer, said in a press release.

“There is virtually no overlap in investment banking and less than a 10% overlap in research coverage,” Thomas W. Weisel, Thomas Weisel’s chairman and CEO, said in a press release. “Our platform adds key growth sectors to Stifel’s investment banking business, particularly in technology, healthcare and energy. Stifel has one of the largest global wealth management groups with nearly $100 billion in client assets, which is a great complement to the combined investment bank.”

Kruzewski added that the merged company will continue to grow the core businesses, expand its offerings and increase its market share.

Last March, Stifel announced it was buying up to 55 branches from UBS Wealth Management, a move that would build on Stifel’s other recent acquisitions, including Ryan Beck in 2007 and Butler Wick in 2008.

Upon the completion of the merger, Kruszewski and Weisel will be Co-Chairmen of the Board and Kruszewski will remain president and CEO of Stifel, which will remain headquartered in St. Louis, with offices in Baltimore, New York, San Francisco and Toronto.

Thomas Weisel will be merged into a subsidiary of Stifel and become a wholly-owned subsidiary of Stifel, the company said.