What a market order promises
Press sell at market and the exchange will normally fill you at once, at a price it doesn’t name in advance. The SEC’s bulletin on order types says a market order will generally be executed immediately, but “the price at which a market order will be executed is not guaranteed.”
Exchange Kraken’s help page names the usual mix-up. “A common mistake is to think the last traded price is what you will get when placing a market order,” it says. A sale takes the highest bids on the book, and a large one takes several price levels in turn, which is where slippage comes from. Kraken’s price terminology page calls the last traded price “purely historical.”
Pairs that refused them on November 10
Not every market accepts one. At 10:15 UTC on November 10, 2026, exchange Coinbase’s public product list flagged 24 of its 515 online pairs as limit only, a mode its documentation says “only accepts limit orders.” The 24 included stablecoin swaps such as USDT-USDC, EURC-USDC, USDS-USD and USD1-USD.
Kraken’s pair data, read just before, put 66 of 1,431 pairs in cancel-only mode and 17 in post-only mode. Its trading rules define cancel only as accepting cancellations and no new orders, and post only as accepting only limit orders marked post-only, so neither takes a market order.
The spread guard
Even an open pair can bounce one. Kraken’s rules describe a Market Price Protection feature that rejects market orders “when the bid/ask spread is wide (typically when the spread is 2.5-20% of market price depending on the currency pair).”
In Kraken’s ticker feed at 10:14 UTC, 233 of the 1,348 online pairs had a bid-ask spread wider than 2.5%. The rules suggest sending a limit order instead, with the limit set at the worst price you would accept, and add that market orders “do not have time-in-force options.”
What EU law adds
MiCA puts a duty on the firm that runs your order. Under Article 78, a provider executing orders for clients must take “all necessary steps” to get the best possible result, weighing price, costs, speed, the likelihood of execution and settlement, size and other factors.
That duty falls away where the firm follows a client’s specific instructions. Article 76(7) separately requires a trading platform’s systems to be able to reject orders that exceed preset volume and price thresholds or are clearly erroneous.
On a busy pair a market order is the quickest way out. On a thin one, look at the bid side of the book and the size waiting there before you press the button.