On a weekend the stock market is shut and index futures are shut. Stock and index perps keep trading. Any move they make is a market price on another venue, set by fewer traders than a weekday would bring. The question is never whether the move is real. It is how much it should count.
Depth is the volume of orders resting near the current price. Fewer firms quote on a weekend, and many traders are away. With less resting on the book, an order of a given size moves the price further than it would on a Wednesday. Depth is not liquidity explains why even the visible depth can overstate what a book will absorb.
Check one: size against the usual move
A move needs a yardstick. On 2 October 2026 the expected daily move on SPY was about 0.46%. That is why NoVo uses half a percent as its threshold on the index perps: a weekend move of that size is about a normal day’s worth. A move well under it is ordinary drift on a quiet book.
Check two: volume behind it
Look at the 24-hour volume and the open interest on the market. A move on rising volume had participation. A move on almost no volume may be a handful of trades. On 4 October 2026, a Sunday, the S&P 500 perp held about $349 million of open interest, so the largest markets do carry weight. Smaller single-name markets carry much less.
Check three: did it hold
A thin book can be pushed by one large order and then drift back. A move that is still there hours later has been tested by other traders who could have faded it. Persistence is the simplest evidence that more than one participant agrees.
Check four: what agrees with it
No single market should be read alone. Do both index perps point the same way? Do the mega-cap perps? If the S&P 500 perp is down and the largest names are flat, the index move has little underneath it. If crypto is falling hard at the same time, the perp may be reflecting a broad selloff, a pattern described in weekend gaps in crypto.
Check five: who is paying
Funding and the premium show whether one side is paying to hold the move. A fall with funding turning negative has shorts paying to stay. A fall with funding at rest may be a single seller and no crowd.
What it is still not
Even a move that passes every check is a price, and no more. When futures reopen on Sunday evening, a far deeper market weighs in and may disagree. The options market reopens with its own positioning, as weekend gamma and thin books discusses.
Trader shows the index perps’ move since the cash close while the market is shut, with the seven largest index names beside them. It sends a push at each half percent, once per direction.