Question 1

What is the “S&P 500 (SPX) Opens Up or Down on May 20?” market asking?

Accepted Answer

It asks whether the following will happen: S&P 500 (SPX) Opens Up or Down on May 20? Traders buy Yes shares if they think it will and No shares if they think it will not.

Question 2

What do the Yes and No prices mean?

Accepted Answer

At the last observation Yes traded at 100.0¢ and No at 0.0¢. A Yes share pays $1 if the market resolves Yes, so its price is the market's implied probability: 100.0% for Yes and 0.0% for No. The two prices add up to about one dollar.

Question 3

When does this market close?

Accepted Answer

Trading is scheduled to close on May 20, 2026. After the close no new trades are accepted and the outcome is settled by the resolution source.

Question 4

How does this market resolve?

Accepted Answer

This market will resolve to "Up" if the official S&P 500 Index open price for S&P 500 (SPX) on May 20 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day. This market will resolve to "Down" if the official S&P 500 Index open price for S&P 500 (SPX) on May 20 is lower than the official S&P 500 Index closing price for SPX on the most recent prior trading day. E.g., ordinarily, a market on Monday would refer to the previous Friday for its most recent closing price, unless that Friday were a market holiday, in which case it would refer to… Resolution source: https://www.wsj.com/market-data/stocks.

Question 5

What is the difference between volume, liquidity and open interest?

Accepted Answer

24h volume ($63.59K) is the dollar value of shares traded in the last 24 hours. Volume measures activity, liquidity measures how easily you can trade, and open interest measures how much is at stake.

Question 6

Who holds the biggest positions in this market?

Accepted Answer

Vultax loaded 24 public holder wallets for this market; the largest ten hold 94.7% of the loaded shares. The Holders view lists them by size on each side, and every wallet links to its trader profile.

Question 7

Where does this data come from and how fresh is it?

Accepted Answer

Prices, the order book, holders and the trade tape come from Polymarket's public order book and data API. Vultax records each observation with its own timestamp (market facts last updated May 21, 10:52 PM) and shows a value as unavailable rather than as zero when a source has not answered.

Question 8

Can I trade this market on Vultax?

Accepted Answer

No. Vultax is a research and paper-trading terminal; it does not execute orders. The trade controls open the official market on Polymarket (https://polymarket.com/event/spx-opens-up-or-down-on-may-20-2026) or the Vultax predictions monitor, where you can track the market and paper trade it.

Trader	Outcome	Shares	Avg entry	Cost basis	Last trade
TraderXI	Down	2.04K	24.7%	$2.04K
enamelgig	Down	272	0.4%	$327

Trader	Current holding value
TraderXI	$0
enamelgig	$0
azahed	$0
AshKaash24	$0
terces5683	$0
Vivid-Handlebar	$0
wanderer666	$0
Mr-X	$0
TENETENET	$0
Yourstrulyy	$0
.Menthe	$0
triklozoid	$0

S&P 500 (SPX) Opens Up or Down on May 20?

Questions about this market