bellSet an opening price

Concepts

The implied open

The opening price a market expects, read from its UP prices.

How it is computed

The implied open is the ladder's lowest edge plus the UP price of every band, where each UP price is the midpoint between that band's best bid and best ask.

Implied open $54.35+4.86 UP, $40–45+4.25 UP, $45–50+2.96 UP, $50–55+1.53 UP, $55–60+0.58 UP, $60–65+0.17 UP, $65–70$40$45$50$55$60$65$70
The example market's UP prices laid end to end from $40. They end at $54.35, the implied open.

Why it adds up

One UP of a band pays the stretch of the opening price that falls inside that band. Lay every band's UP end to end and they cover the whole ladder below the opening price, so the ladder's floor plus all of them is the opening price itself. Their prices add up to what the market expects it to be.

When there is one

Every band's UP book needs both a bid and an ask. While any is missing, the app shows a dash in place of the implied open and the bell lies flat on its axis.

The bell in the app

The bell over the ladder is a lognormal curve fitted to the same UP midpoints, so the spread of prices the market expects is visible at a glance. Its dotted tick is the implied open, computed exactly as above. Under the price, a line traces the implied open over the last stretch of time Bell has indexed.