The S&P 500 perp shows one number on a weekend. The perps on the seven largest names show seven more. Read together they sort a weekend move into a small set of shapes, and each shape says something different about what moved the index perp.
All seven in the same direction
When every name is up or every name is down by roughly similar amounts, the cause is unlikely to be about any one company. Something that touches all large stocks at once is being priced: rates, policy, a geopolitical event. This is the weekend version of a broad move, the idea behind market breadth, seen through seven names instead of hundreds.
Seven is a narrow window on breadth. All seven are large technology-linked companies. They can agree with each other while the rest of the market does something else. A broad reading across the seven says the move is wider than one stock. It does not say the whole index took part.
One name doing the work
When one name sits at the top of the list with a move several times the others, and the rest are near flat, the index perp’s move has a single source. Look for news on that company. The index move is then a by-product of one stock’s repricing. That matters more for the Nasdaq 100, where these names carry more of the index, than for the S&P 500.
The seven are split
Some up and some down, with the index perp near flat, usually means company-level stories that cancel at the index level. The index reading is calm. The single-name readings are not. A trader in index options sees a quiet weekend. A trader in those names sees a busy one.
The index perp moved and the seven did not
This is the pattern to slow down for. If the index perp is off by a meaningful amount and none of the seven has moved, either the move is coming from parts of the index the list does not cover, or it is a feature of the index perp’s own book. On thin weekend depth one order can do it. How far to trust a small move lists the checks.
Using the shape with the dealer map
The shape does not change where the gamma flip or the walls sit on SPY and QQQ. It changes how much to read into the implied level. A broad move that carries the implied level across the flip has more behind it than a move of the same size resting on one stock. Both are still prices on another venue and neither is a forecast of the open.
The list is unweighted and sorted by size of move, for reasons set out in which mega-cap is carrying the index. Trader shows it beside the index perps on the Perps & Futures tab whenever the cash market is shut.