The two companies will form a joint venture to create and provide the service, called Block Alert, which will be independent, anonymous and powered by ITG's Posit crossing network.

In a statement, the companies say the venture will partner Merrill Lynch's global distribution with ITG's technology-enabled trading to provide an expanded, singular liquidity pool for block orders.

Ray Killian, chairman, president and CEO of ITG, says: "Through this new joint venture, ITG's clients will have access to a greater global pool of liquidity made available by Merrill Lynch's distribution network. This will be a major infusion to our already robust liquidity pool, increasing matching opportunities while maintaining the confidentiality and anonymity."

Roll out of the service is expected to begin in the US in the second quarter of 2006.

Earlier this year Credit Suisse said it was looking to register its internal crossing network, CrossFinder, as an alternative trading system in a bid to grow liquidity and boost transparency.