iShares Core S&P Mid-Cap ETF

Expense ratio (Total Expense Ratio) is the annual fee the fund charges, deducted from assets. It’s the headline cost, but not the full picture.

Tracking Difference measures how much the fund actually lags (or leads) its benchmark index per year. This is the single best measure of true cost — it captures the expense ratio plus all other drags like sampling error and tax withholding. A lower (or negative) value is better.

TD Consistency measures how stable the tracking difference is from year to year. A low value means predictable, reliable costs; a high value means costs can vary significantly.