GLD vs IAU vs SGOL: Tracking Error and Why It Matters Long-Term

If you are buying a gold ETF, you have three serious options: SPDR Gold Shares (GLD), iShares Gold Trust (IAU), and abrdn Physical Gold Shares (SGOL). They all hold physical gold in London or Zurich vaults. Their differences sound trivial until you compound them over a decade.

The expense ratios

• GLD: 0.40% annually (oldest, most liquid, $58B AUM)
• GLDM (mini-GLD): 0.10% annually (newer, lower-cost cousin)
• IAU: 0.25% annually (iShares, $30B AUM)
• SGOL: 0.17% annually (abrdn, $4B AUM)
• BAR (GraniteShares): 0.175% annually (smaller, niche)

The tracking error reality

Expense ratio is not the same as tracking error. Tracking error is how much the ETF's actual return diverges from spot gold. Over 5-year windows, the rough numbers look like:

• GLD: -0.42% per year average tracking deficit
• IAU: -0.27% per year
• SGOL: -0.18% per year
• GLDM: -0.11% per year

The tracking deficits closely match the expense ratios because all three are highly efficient grantor trusts with minimal transaction costs.

The compounding math

Over 20 years, a 0.40% annual deficit compounds to roughly 7.7% of total return. A 0.10% annual deficit compounds to about 2.0%. On a $100,000 holding that doubles to $200,000 in real spot terms, the GLD investor ends with $192,000 and the GLDM investor ends with $198,000. Six thousand dollars on a single holding for the same exposure.

"For tactical positions of less than a year, GLD's liquidity advantage outweighs its expense ratio. For buy-and-hold, GLDM or SGOL is the rational choice." - quantitative strategist, multi-strat hedge fund

Liquidity considerations

GLD trades roughly 8 million shares per day. IAU trades 5 million. SGOL trades 1 million. For institutional-size trades, GLD's tighter spreads can save more than the expense ratio difference. For retail-size trades, all three have spreads tight enough that liquidity does not matter.

The vault location difference

Both GLD and IAU custody primarily at HSBC London. SGOL custodies in Switzerland (Zurich). For investors specifically concerned about concentration risk in London vaults, SGOL provides genuine geographic diversification. PHYS (Sprott) custodies in Canada and offers physical redemption, which neither GLD, IAU, nor SGOL do.

Tax treatment

All three are taxed as collectibles in the US: 28% maximum long-term capital gains rate, not the standard 20%. This is the same as physical bullion. The ETFs all issue annual K-3 (formerly K-1) forms. The collectibles rate makes Gold IRAs more attractive than they would be if ETF gains were taxed as ordinary capital gains.

Recommendation

For a long-term gold position over $50,000, use GLDM or SGOL. For tactical trading or positions under $10,000, use GLD for liquidity. Avoid the smaller ETFs (BAR, OUNZ, AAAU) unless you have a specific reason because their tracking error tends to be wider than their expense ratios suggest.

Bottom line: Tracking error is the silent cost of ETF ownership. Pay attention to it because it compounds, and pick GLDM or SGOL over GLD for any holding you plan to keep more than 18 months.