Count last-trade direction within the stated universe
For the snapshot definition, TICK = U - D, where U and D count eligible stocks classified as upticking or downticking. Direction refers to recent trades, rather than the change from the previous daily close. Keep the provider convention for unchanged trades and eligible securities: the label NYSE alone does not establish a common-stock-only universe or identical inputs across vendors.
- Hypothetical snapshot: 1,650 stocks are classified up, 1,050 down and 300 remain outside either category under the assumed classification. TICK = 1,650 - 1,050 = +600. The 300 are not silently counted as down.
- In that example, 1,650 / 2,700 = 61.11% of the classified stocks are up. The +600 reading alone cannot establish that percentage because it does not disclose the denominator.
- If a universe has N eligible stocks and each can contribute at most +1 or -1, the snapshot lies between -N and +N. N is not a fixed historical constant; listing changes and coverage changes affect comparisons.
- An index, ETF or futures OHLCV bar does not contain the last-trade direction of every NYSE stock. Candle direction, volume or a small custom basket cannot exactly reconstruct the exchange-wide count.