iShares, the world’s biggest ETF company, filed with the Securities and Exchange Commission for a 10-for-1 share split of its iShares COMEX Gold Trust (NYSEArca: IAU) in a move designed to make the shares less expensive and potentially more accessible to investors.

The split is payable on June 23, 2010, to shareholders of record on June 21, the filing said. The share split will cut IAU’s price by a factor of 10. It settled today at just over $120 a share, meaning it would cost a bit more than $12 a share if the split took place at today’s price. The ETF’s price has risen almost 12 percent this year and has about tripled since it was launched in early 2005.

Gold has been in a long-term rally for almost 10 years, and it has become even more popular in the past several weeks since problems in the eurozone sparked renewed anxiety about the frailty of the U.S. expansion. IAU’s competitor, the SPDR Gold Trust (NYSEArca: GLD), was the single most popular ETF in the U.S. last month, according to data compiled by IndexUniverse.com.

GLD raked in $4.33 billion in new money in May, bringing total assets to $49.21 billion. That makes GLD the second-biggest U.S. ETF after the SPDR S&P 500 (NYSEArca: SPY), which had $70.62 billion at the end of last month.

IAU, by contrast, now has about $3.3 billion in assets, iShares said in a press release on the share split. IAU has almost 28 million shares outstanding, meaning it will have about 280 million after the split.

Officials at iShares weren’t immediately available to comment on the split, particularly on how it might adversely affect investors who pay commissions on a per-share basis when they trade the ETF.