Shares of Denver-based investment firm Janus Capital (JNS) were up sharply Monday after London's Henderson Group announced it had agreed to acquire the firm, sending Janus shares higher. The combined fund is estimated to manage roughly $320 billion and is expected to apply for admission to trade on the New York Stock Exchange as a primary listing, once the tie-up nabs regulatory approval. Shares of Janus were trading up about 15% on the announcement.

This article was written by a staff member of TheStreet.