0DTE (zero days to expiry)
An option that expires today. Everything about options is compressed into hours: the payoff, the decay, and the mistake.
Glossary
One definition per term, used everywhere: the same data renders this index and the inline references inside every course and case study.
ATM offering (at-the-market)
A standing program that lets a company drip new shares into the open market at whatever the current price is — no roadshow, no announcement per sale. If a company has one loaded, a price spike is not just a rally; it is
Borrow fee
What it costs, per year, to borrow shares so you can short them. This is the price signal from the people with actual money on the line — the stock lenders. When shorts are genuinely trapped, this price rips higher withi
Breakeven (options)
For a call: the strike price plus what you paid. The stock does not just have to go up — it has to go up PAST this line by expiry for the trade to make a single dollar at settlement.
Convertible-arb hedge
Shares sold short not as a bet the stock falls, but to hedge convertible notes the same investor owns. These shorts show up in the headline Short interest (SI) number, but they are not directional bets and are far less e
Days to cover (DTC)
How many days it would take every short seller to buy their way out, if they all used a normal day's trading volume. Under one day means the exit door is wide open; many days means a crowd pressing through a narrow door
Dilution
The company selling new shares, making every existing share a smaller slice of the business. For a stock that just spiked, it is instant gravity — and for call options on that stock, it is the fastest kill there is.
Gamma (dealer hedging)
When crowds buy call options and dealers end up net short those options, the dealers buy stock to stay hedged — and the higher the stock goes, the MORE stock they need. That mechanical feedback loop amplifies moves in bo
Implied volatility (IV)
The market's priced-in expectation of how much a stock will move — and therefore what you PAY when you buy an option. High IV is not a forecast that you will win; it is a high price of admission.
Re-rating
The market changing what it will pay per dollar of a company's earnings, on new information. The business is the same size today as yesterday — but the market now believes the future is differently shaped, so the multipl
Rebate (stock loan)
The interest a short seller EARNS on the cash collateral they post when borrowing shares. Here is the one-sentence read: a POSITIVE rebate means borrowing is easy — the opposite of squeeze conditions.
Short interest (SI)
The total number of shares that have been sold short and not yet bought back. It is a snapshot of how big the bet against a stock is — but it publishes on a schedule, twice a month, with a lag of more than a week. By the
Short volume
How many of today's SELL orders were marked as short sales. It publishes daily, which makes it tempting to read as a live squeeze gauge — but it structurally cannot show you the thing squeeze-watchers want most: shorts b