* Chairman Nasser Al-Kharafi dies of heart attack - source
* Kharafi Group was proponent of failed Zain stake sale
* Zain, National Investments shares slump in Kuwait trade
(Adds details, background)
By Eman Goma and Dinesh Nair
KUWAIT/DUBAI, April 17 (Reuters) - The billionaire chairman of the Kuwaiti conglomerate Kharafi Group, a major shareholder in telco Zain , has died in Cairo from a heart attack, a Kharafi Group source said on Sunday.
Nasser Al-Kharafi headed the Kuwaiti family-owned firm which had stakes in several listed firms in the Gulf state. The group was also the major proponent of a proposed $12 billion stake sale in Zain to UAE's Etisalat .
The Kharafi Group has not yet made any official announcement but news of the unexpected death shook Kuwaiti markets with companies having links with the group plunging in early trade.
Nasser Al-Kharafi, aged 67, was ranked 77th in the 2011 Forbes list of richest people in the world and was estimated to be worth $10.4 billion. His empire spanned sectors including construction, manufacturing and retail and had investments in Kuwait's leading financial institutions and listed firms.
Zain shares were trading down 3.3 percent on the Kuwaiti bourse at 0850 GMT. They dropped as much as 5 percent earlier in the day. Shares in National Investments , another Kharafi Group-owned company, fell 5.1 percent.
Shares in National Bank of Kuwait , the Gulf state's biggest lender, also dropped 1.7 percent. Nasser Al-Kharafi was on the lender's board and the group had a stake in the bank.
The Kharafi Group, walloped by the global financial crisis and a property slump in Kuwait, has been keen to offload its Zain position for more than a year. In 2009, its deal to sell a 46 percent stake to an Asian consortium fell through.
The group owns a 12.7 percent stake in Zain through one of its units, according to bourse data, but analysts estimate Kharafi's stake to be around 20 percent through other firms it controls.
The Etisalat deal fell apart in March after the telco pulled out, citing difficulties with Zain's divided board, extended due diligence and regional unrest. [ID:nLDE72J01L]
Last week, Zain shareholders elected a new board, including a top executive from the Kharafi Group, and approved a $3 billion dividend for 2010. [ID:nLDE73B03S] (Additional reporting by Rachna Uppal, Editing by Reed Stevenson)