State Street Global Advisors literally struck gold last year with the introduction of the streetTracks Gold Shares ( GLD) exchange-traded fund. Now, as the gold ETF approaches its first birthday, the question is whether State Street can keep the hits coming. Since it started trading on the New York Stock Exchange on Nov. 18, 2004, the GLD, whose shares represent one-tenth the price of an ounce of gold bullion, has exploded to more than $3.15 billion in assets. It trades, on average, close to 2 million shares a day. In terms of price, the GLD is up 5% since its debut, rising to $46.66 from $44.43, along with the price of gold. Making the GLD's success all the more lustrous is that it comes at the expense of rival Barclay's offering, the iShares Comex Gold ( IAU) ETF, which first started trading a few months after the GLD in January. At last count, the IAU had assets of $186 million and trades in the neighborhood of 84,000 shares a day. Expenses for both funds are similar, at 40 basis points, a sum Morningstar analyst Karen Wallace calls "pretty reasonable" considering that a typical precious metal fund in the category costs 1.67%. Analysts agree that first-mover advantage and the superior ticker symbol -- how many traders truly remember that AU is the symbol for gold on the periodic table? -- were the prime reasons for State Street's first head-to-head victory over its powerful rival in years. Says Lipper's Don Cassidy, "First mover advantage is huge in ETFs. If it works, then traders stick with it." Nevertheless, the GLD also was the culmination of years of effort and coordination by State Street, along with the fund's sponsor, the World Gold Council. And some analysts say it's the big win that may just rejuvenate the company in the escalating ETF wars.