(Bloomberg) -- Virtu Financial Inc., a high-speed trading firm, is seeking to acquire independent brokerage Investment Technology Group Inc., according to people familiar with the matter.

Virtu is working with a financial adviser to pursue ITG, said the people, who asked to not be identified because the matter isn’t public. The companies have recently been holding talks about a deal, they said. No decision has been made and ITG could decide to remain independent, they said.

Representatives for Virtu and ITG declined to comment.

ITG shares rose as much as 12 percent before they were temporarily halted in New York trading. The stock rose to $24.73 at 11:20 a.m., valuing ITG at $816 million. Virtu rose 4.9 percent to $21.65, valuing it about $4.1 billion.

ITG, based in New York, offers equity, options, derivatives and other trading products. It also runs a private trading platform known as a dark pool.

Buying the company would give Virtu more access to the big, institutional investors that trade through ITG. Virtu acquired rival high-frequency trading firm KCG Holdings Inc. last year for about $1.3 billion, adding a business that executes orders for retail customers.

--With assistance from Matthew Monks.

To contact the reporters on this story: Nick Baker in Chicago at nbaker7@bloomberg.net;Annie Massa in New York at amassa12@bloomberg.net

To contact the editors responsible for this story: Margaret Collins at mcollins45@bloomberg.net, ;Elizabeth Fournier at efournier5@bloomberg.net, Josh Friedman

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