How to Choose a Broker: Fees, Execution and What Matters

Every large US retail broker charges zero commission on US stocks and ETFs now. So the old comparison is over, and the new one happens in places the marketing page will never show you: where your order goes, what you get paid on idle cash, what you pay to borrow, and how much of your money the firm is legally required to return if it collapses. Four questions. None of them appear in an advertisement.

Start with the account, then pick the firm

The account type decides your tax treatment for decades. The broker decides pennies.

A taxable brokerage account has no contribution limit and no withdrawal rules, and the cost is that dividends and realized gains show up on your return every year. A traditional IRA gives you a deduction now and taxes the withdrawals later. A Roth IRA takes after-tax money and the growth comes out untaxed in retirement. A rollover IRA receives an old workplace plan without triggering tax. Joint accounts, custodial accounts for a minor, and trust accounts exist at most firms and each carries its own paperwork.

Contribution limits and income phase-outs for IRAs change most years, so check the current figure at the IRS before you fund anything.

Confirm the firm supports the account you actually need. Some brokers handle Roth conversions and inherited IRAs smoothly. Some make you call. Tax-efficient investing covers which account should hold which asset, and that placement decision outlasts every other choice on this page.

One more split, and it is the one beginners get wrong: a cash account settles every purchase with money you already have, while a margin account lets you borrow against your holdings and also lets your broker lend your shares out. Margin accounts avoid settlement delays on the proceeds of a sale, which is convenient. They also expose you to a margin call, and to the pattern day trader rule at $25,000 of equity if you make four or more day trades in five business days.

What commission-free is paying for

Your order leaves the app and goes somewhere. In most cases it goes to a wholesale market maker, a firm that takes the other side of retail orders from its own book, and that firm pays your broker for the privilege of receiving the order. That payment is payment for order flow, and it is disclosed every quarter under SEC Rule 606.

Why would anyone pay for your order? Because retail orders are, on average, harmless. A person buying 40 shares of a large company is unlikely to know something the market maker does not, so filling that order is a low-risk way to earn part of the bid-ask spread, and a wholesaler running millions of such fills a day turns a fraction of a cent per share into a real business.

Here is the arithmetic from your side. A stock quoted 49.98 bid, 50.02 ask has a four cent spread. Buy 200 shares at the ask and sell instantly at the bid and you are down 200 x $0.04 = $8, which is your cost of round-tripping the position. The commission was zero the entire time.

Market makers and liquidity explains who is on the other side and why the spread exists at all.

Execution quality, which you can measure

Price improvement means your order filled at a better price than the quote showed. With the market at 49.98 by 50.02, a buy filled at 50.00 improved your price by two cents a share.

Two cents sounds like nothing. Run it: 200 shares is 200 x $0.02 = $4 on one trade, and a person who places 100 orders a year at that size collects 100 x $4 = $400 of improvement they will never see itemized anywhere, which is real money for anyone whose entire reason for switching brokers was a $50 transfer bonus.

Two disclosures let you check this. SEC Rule 606 reports say where your broker sent your orders and what it received. SEC Rule 605 reports come from the market centers themselves and cover fill quality: effective spread, how often orders were price improved, and speed of execution. Both are published quarterly. Both are free. Almost nobody reads them.

There is a second reason to read the 606 report. It tells you whether your broker sends everything to one destination or splits the flow, and a firm routing effectively all of its marketable orders to a single wholesaler has handed that wholesaler the entire relationship, which is fine when the fills are good and leaves you with no alternative when they are not.

Your order type changes the answer as much as your broker does. A market order accepts whatever the book offers. A limit order caps your price and risks no fill at all. Stock order types explained has the worked numbers on each one, and the choice matters most in thin stocks, at the open, and in extended hours.

SIPC covers the firm failing

SIPC protection applies when the brokerage itself fails and customer assets go missing. The limit is $500,000 per customer per firm, of which at most $250,000 may be cash. If your broker collapses, SIPC works to restore the securities and cash that should have been in your account.

Now the part people misread. SIPC has nothing to do with investment performance. A stock that falls 80 percent is an uninsured event and always will be. The protection also excludes futures contracts, most cryptocurrency held at a broker, fixed annuities and unregistered investment contracts.

Excess-of-SIPC coverage is common at the larger firms, arranged privately through insurers and usually described somewhere in the small print with a high aggregate limit. Read what it says. It is genuine protection against a custody failure and it is still silent about a position that went to zero on its own.

Uninvested cash is its own question. Many brokers sweep idle balances into partner banks, where FDIC insurance applies at $250,000 per depositor per bank, and a sweep spread across several banks can carry a much larger total. Other brokers sweep into a money market fund, which is a security under SIPC and carries no FDIC coverage. Ask which one your firm uses and what it pays, because the yield on swept cash varies enormously between brokers and it is pure profit for the ones paying near zero.

	SIPC	FDIC
Protects against	The broker failing	The bank failing
Limit	$500,000, cash capped at $250,000	$250,000 per depositor per bank
Covers market losses	No	No
Applies to swept cash	Only if held at the broker	Only in a partner bank program

Margin rates and the tier you land in

Borrowing against your portfolio is a loan, and brokers price it in tiers by balance size. Small balances pay the highest rate. Very large balances pay a few points less.

A $10,000 margin loan at 12 percent costs $10,000 x 0.12 = $1,200 a year. The same loan at 6 percent costs $600. That $600 difference is larger than every commission most retail investors will pay in a decade, and it accrues daily whether the position is up or down.

The margin calculator runs the maintenance arithmetic: how far a position can fall before the broker issues a call, and what happens to the equity in your account on the way down. Brokers can raise maintenance requirements on a volatile stock without warning and can liquidate your positions to satisfy a call without asking you first. Both of those are in the agreement you signed.

The short list worth comparing

Six things. Most comparison articles list twenty and bury these.

What to check	Why it matters
Rule 606 routing and price improvement	The largest hidden cost on every order you place
Yield paid on uninvested cash	Silent drag on any account holding a cash buffer
Margin rate at your balance tier	Hundreds a year if you ever borrow
Fees for transfers out, wires, paper statements and options contracts	The charges that survived the commission cuts
Account types and whether the ones you need are supported	Roth conversions, inherited IRAs, custodial accounts
Fractional shares and automatic investing	Determines whether small regular contributions work cleanly

Options traders should check one more line. Per-contract fees survived the commission cuts almost everywhere, and a firm charging sixty-five cents a contract costs a person trading ten contracts a month 10 x $0.65 x 12 = $78 a year, which sounds trivial until you compare it with a firm charging half that and notice you have been paying for nothing in particular.

Platform quality matters more than beginners expect and less than reviews suggest. You need a clear order ticket, visible cost basis, a tax document that arrives in January, and a support line that answers. Charting, screeners and news feeds are available free elsewhere.

If two brokers look identical after all that, pick the one whose interface you find boring. Excitement in a trading app is a design goal for the firm, and it is not one of yours.

Open the account, fund it, and put the first purchase through as a limit order so you can watch the fill. How to invest in stocks walks through that first order step by step, and how the stock market works follows that order from your screen to the exchange and back through settlement, which is the last piece of the picture a broker sits inside.