In a statement, DBG said the organisation will become a 100 per cent owned subsidiary in a cash deal worth $10 million (Â£6.7 million). The deal is expected to formally complete by the end of January 2009, subject to regulatory approval from Germany's competition commission.
DBG said MNI's access to international news rooms, government agencies and organizations such as the World Bank and the International Monetary Fund will be used to boost its real-time information streams for the markets, aiding investors' decision making.
The group's managing director Holger Wohlenberg said: "Market participants pursuing automated trading strategies and quants will benefit from new trading signals for their algorithms."
MNI currently has a staff of 85 posted at 12 offices in Europe, the United States and Asia.
DBG already operates the Xetra trading platform and the Frankfurt Stock Exchange, one of the world's biggest fully-electronic cash markets. It also owns the Eurex futures and options trading platform and the Clearstream settlement services for fixed-interest securities and shares.