Good til cancelled (GTC)

The instruction most retail platforms apply by default to a pending order. Where good for day expires with the session, a good til cancelled order survives it and keeps working, day after day, until the price reaches it, until it is cancelled, or until something outside the order removes it.

That last clause is the part the name obscures, because until cancelled is bounded in practice. Brokers and venues impose a maximum life, commonly a number of months, after which resting orders are purged. A contract expiry, a corporate action, an instrument being delisted or a change to the instrument's specification can all cancel or invalidate an order that has been sitting for weeks. Conventions for adjusting a resting order's price after a share split or a dividend adjustment also differ between firms rather than following one standard.

Two practical points follow. In most retail contracts for difference the order is held by the broker rather than resting on an exchange, so it exists only while the broker's system holds it and is subject to that firm's housekeeping. And an order left working for weeks can be triggered by a price nobody is watching, including on a gap, which is why a periodic review of resting orders is a common convention among traders who leave them out.