Pakistan plans to sell a 40 percent stake in its stock exchange in coming months, and Turkey's Borsa Istanbul has expressed some initial intent, the head of the bourse said on Monday.The sale will happen at the end of this year or in early-2017, Pakistan Stock Exchange Managing Director Nadeem Naqvi told an investment conference organized by Renaissance Capital in London.Naqvi said the bourse would launch an official process over the next two weeks to invite expressions of interest from potential investors. It has already reached out to the London, Shanghai, Turkish and Qatar stock exchanges, he added.He said, however, that only Borsa Istanbul had responded so far.The stake sale will be followed up with a listing of a further 20 percent of stock exchange shares in the domestic market, Naqvi added.The privatization of almost 70 state-owned companies is a major element of a $6.7 billion three-year International Monetary Fund (IMF) package that helped Pakistan stave off default in 2013.The deal ends in September and the IMF has continued to release loan installments despite missed targets.