The advertised margin rate is a true number about someone else's balance. Margin is tiered, and you almost certainly pay the bottom tier.

- A broker advertising 8% may charge you 10.5% if that rate only kicks in above $500,000 - Interactive Brokers' tiered rates genuinely undercut rivals at big balances; at small balances the edge shrinks - Two points on a $50,000 balance is $1,000 a year: a vacation, not a rounding error - Margin interest accrues daily and compounds; the schedule is the only truth - Large balance? Call and ask; published rates are the opening bid, not always final

BrokerMatch ($2.99 one-time) compares margin tiers at your actual balance, so you skip the headline and see your rate.