UPDATE 1-ASMI sale of shares in HK unit disappoints

* ASMI to sell 8-12 percent of ASM Pacific in placement

* Investors had hoped for a larger stake sale

* Shares fall as much as 16 percent

(Adds details, share move, quotes)

AMSTERDAM, March 13 (Reuters) - Dutch semiconductor equipment maker ASM International NV is selling a smaller-than-expected stake in its Hong Kong-listed unit, disappointing investors who had hoped a break-up of the firm might create more money for shareholders.

ASMI's shares fell as much as 16 percent on Wednesday to their lowest since November, after it said it would sell between 8 percent and 12 percent of the total outstanding share capital in ASM Pacific Technology in a share placement.

The sale, launched on Wednesday, could raise up to $457 million, IFR reported, citing a term sheet of the transaction.

ASMI consists of its own front-end processing, or production, of silicon chips, and the back end - the dicing and packaging of microchips - held by ASM Pacific.

The Dutch company has been at war with some investors over its valuation since 2006, because its majority stake in ASM Pacific has consistently been worth more than ASMI's market capitalisation.

ASMI's shares also trade at a substantial discount to those of its peers, according to StarMine Estimates, based on measures including the ratio of price to net asset value, the ratio of price to cashflow, and the ratio of enterprise value to EBITDA (earnings before interest, tax, depreciation and amortisation).

ASMI's founder and largest shareholder, Arthur del Prado, told investors in May 2012 that he favoured splitting up the group, and there were few synergy benefits in keeping ASMI combined with ASM Pacific.

Since then, ASMI has spent several months looking into how best to unlock its full value for investors, and said it had considered several options including a full or partial placement or sale of its stake in ASM Pacific, a spin-off of shares in ASM Pacific, and several merger alternatives.

"Expectations were high and they need to do more than this," said Robin van den Broek, analyst at ABN Amro.

"If you take 10 months and then you only sell 8 to 12 percent, you're not really solving the problem of the holding company discount."

Following the planned divestment, ASMI will own between approximately 40 percent and 44 percent of the shares in ASM Pacific.

HSBC and Morgan Stanley were hired as joint bookrunners on the deal.

($1 = 7.7568 Hong Kong dollars)

(Reporting by Sara Webb; Editing by Mark Potter)