The managers have been allocated $3.2 billion out of the reserves, which stood at a record $12.505 billion in the week ending May 1.
"We are finalising agreements with them," Ishrat said.
"Once the legal agreements are signed, the money would be transferred."
Ishrat Husain did not name the managers or say when the deal would be completed, but did say they would manage the funds against a benchmark.
The SBP's direct reserve holdings are $10.889 billion, while the rest is with the commercial banks.
Last year, the SBP announced plans to invest a portion of foreign exchange reserves through international investment banks in an attempt to make higher profits on its holdings.
The SBP governor said the government would have further recourse to the international capital market following the success of the recent $500-million Eurobond issue.
"We went in for the Eurobond issue because we wanted to remain in touch with the market," he said.
"This was a strategic re-entry for us, particularly in the European market and the Asian market, where we hadn't gone for the last six or seven years."
The SBP may give more time to one or two banks that fail to reduce holdings in the stock market to 20 percent of their equity before a year-end deadline, its governor said.
The State Bank of Pakistan issued the directive for banks and financial institutions to cut their exposure in stocks last August.
"There are only one or two individual banks which feel that if they liquidate their portfolio too rapidly, then it may have some repercussions on the market," State Bank of Pakistan Governor told Reuters.
He said the central bank had told them to do their best and would review their cases at the year-end.
"We have 40 banks who are engaged in equity trading. It's only one or two banks which may possibly have some kind of problems and we are open to listen to them," he said."
The SBP governor lent forward on his swivel chair to confide his anxieties over the hordes of jobless young men roving the streets.
"If you see the number of youths that are without jobs, that worries you a great deal," he said.
"I think that the fact that we still have a lot of challenges for this economy. That keeps me awake," said the ex-World Bank economist, who has written extensively on poverty issues and against the economic elites in his country.
When the Urdu poetry and music loving economist returned to his homeland in 1999 to take over the central bank shortly after Musharraf came to power, Pakistan's international currency reserves were worse than zero.
But Ishrat bridles at recurring suggestions that Pakistan is propped up by US funding, and the economy would haemorrhage if Washington withdrew its favour.
He said the reform programme rather than the foreign aid led the turnaround in the economy.
"The argument is that it's a dependence on the US which keeps the economy floating and if the US withdraws then the economy collapses - but the fact is that if the US doesn't give any grant we still are okay, we don't have any difficulty."
Foreign direct investment in the first nine months of this fiscal year was a touch below last year's meagre total of $658.2 million, and there has been a net outflow of $45.5 million of foreign portfolio funds.
While he is still struggling to get some of the external flows right, Ishrat says his monetary policy is achieving its aim of bringing the economy on track for the six percent growth that the International Monetary Fund sees Pakistan hitting next year.
Interest rates hit their lowest levels ever-early last year, and have now bottomed out, Husain said.
But he is not rushing to put rates up despite economists' expectations inflation will overshoot the central bank's target and reach around five percent this fiscal year.
"If you do it to soon you are jeopardising the economic growth, if you don't do it you might be left with a high inflation rate. That is the balancing act.
"That is what worries me a great deal."
Now, he says inflationary pressures are coming from high oil and food prices. Tightening monetary policy cannot cure that.