GLD is the largest ETF to invest directly in physical gold. NAV is determined using the LBMA PM Gold Price (formerly the London PM Gold Fix), so GLD has an extremely close relationship with spot prices. Its structure as a grantor trust protects investors; trustees cannot lend the gold bars. However, taxes on long-term gains can be steep, as GLD is deemed a collectible by the IRS. It is extremely liquid, trading at miniscule spreads. Although more expensive to hold than competitor IAU, GLD is typically cheaper to trade. Also, GLD's NAV has a larger handle, which corresponds to more gold exposure per share. Investors paying per-share commissions should find this fact appealing.