Life of a Stock Trade
You don't buy a stock from 'the market'. Your order takes a route through at least four institutions you've never heard of, and you don't own anything until tomorrow.
The walkthrough
Tapping "Buy" in an app feels instant, but it kicks off two distinct phases: execution (finding a counterparty and agreeing a price in milliseconds) and clearing & settlement (legally moving the shares and cash, which finishes the *next* business day).
Order routing, where your order actually goes. Your broker (Robinhood, Schwab, Interactive Brokers) almost never sends the order straight to an exchange. For retail orders it usually routes to a wholesaler / market maker like Citadel Securities or Virtu, who pays the broker for the order flow (PFOF) and fills you at or inside the public best price. Larger or institutional orders go to a lit exchange (NYSE, Nasdaq) or a dark pool. Wherever it lands, a *matching engine* pairs your buy with someone's sell using price-time priority.
The fill, a contract, not a transfer. The instant your order matches, you have a legally binding trade: a price and quantity are locked in. But you don't hold the shares yet. The exchange reports the trade to a clearing house, in the US the NSCC (part of DTCC). No money or stock has actually changed hands.
Clearing & settlement, the slow, invisible part. The clearing house steps in as central counterparty (CCP), guaranteeing the trade so neither side worries about the other defaulting. It nets all of a member's buys and sells down to a single obligation, then on T+1 (one business day after the trade, since the US moved off T+2 in May 2024) the shares and cash swap on the books of the DTC depository. Only then do you legally own the stock.
Who takes a cut, and the risks. Retail commissions are often £0/$0, but you pay implicitly through the spread, PFOF, and tiny regulatory fees. The real failure modes hide in the slow phase: a failed settlement if the seller can't deliver shares, or counterparty risk during the day the clearing house is on the hook, which is exactly why the CCP demands margin from its members.
The rail map
The equity trade lifecycle
- 1You
Tap "Buy 10 shares" in the app, an instruction, not a transfer.
- 2Broker
Receives the order and decides where to route it, often selling the flow.
- 3Market maker / exchangewhere value leaks
A matching engine pairs your buy with a sell; price and quantity lock in.
- 4Clearing house (CCP)highest cost / risk
NSCC guarantees and nets the trade, taking on counterparty risk for the day.
- 5Depository (DTC)where value leaks
On T+1 the shares and cash actually swap on the books, now you own it.
Glossary
Execution
The moment your order is matched against a counterparty and a price/quantity are agreed.
PFOF (payment for order flow)
A rebate a market maker pays your broker to send it retail orders, funding "zero-commission" trading.
Clearing house / CCP
A central counterparty (e.g. NSCC) that sits between buyer and seller and guarantees the trade.
Netting
Collapsing all of a member's offsetting buys and sells into one net obligation to settle.
T+1 settlement
The rule that shares and cash legally change hands one business day after the trade (US since May 2024).
Failed settlement
When a party cannot deliver the shares or cash on the settlement date, forcing a buy-in or penalty.
Check yourself
1.You tap "Buy" and instantly see "Filled". What do you legally own at that exact moment?
2.Your broker charges £0 commission. How does the trade still generate revenue from your order?
3.What is the main job of the clearing house (CCP) between trade and settlement?
4.Why does the clearing house demand margin from its members during the settlement window?
5.In the US, when do the shares and cash from a normal stock trade actually change hands?