NEW YORK : Private equity firm GTCR is poised to garner a return of about two times its investment in Worldpay, after the sale of its 55 per cent stake in the payments processor to Global Payments, people familiar with the matter said on Thursday. Such a big windfall has become increasingly rare in the private equity industry, which has been starved of large exits during the last two years when high interest rates froze up financing markets and slowed down the pace of large leveraged buyouts.