* NCB picks HSBC, GIB Capital as IPO advisers - statement
* Share sale expected this year
* IPO likely to be one of largest ever in Saudi (Adds valuation, context, quote)
RIYADH, April 9 (Reuters) - National Commercial Bank IPO-NACO.SE, Saudi Arabia's largest lender, chose HSBC's Saudi Arabian arm and the investment banking unit of Gulf International Bank as advisers on what is expected to be one of the largest ever initial public share offerings in the kingdom.
Bankers estimate a deal size of between 15 billion and 20 billion riyals ($4 billion-5.33 billion).
NCB chairman, Mansour al-Maiman, said in a statement on Wednesday that the bank was preparing to list its shares on the Saudi stock exchange this year.
"The flotation will contribute to deepening the Saudi financial market, and will allow Saudi citizens to subscribe to a venerable financial institution," he added in the statement.
No valuation for the share sale's size or the price at which the shares will be offered was given.
Currently, NCB is majority-owned by the state Public Investment Fund. It held assets worth around $101 billion at the end of 2013 and made net profit of $2.1 billion last year.
Once listed, analysts have said it is likely to be one of the three largest stocks on the Saudi exchange - which would put its market capitalisation north of $30 billion.
Saudi Arabia does not allow direct foreign investment in its stock market and the share sale will only be open to local investors. However, the Saudi market is very liquid and, given the desirability of the stock, demand is expected to be high.
Finance Minister Ibrahim Alassaf announced in February that 15 percent of the bank would be sold by the PIF, with a further 10 percent being transferred to a second state-owned investment fund - the Public Pension Agency. ($1 = 3.7503 Saudi Riyals) (Reporting by Angus McDowall; Writing by David French; Editing by Elaine Hardcastle)