McClellan Oscillator: Breadth Momentum (EMA19 − EMA39 of Net Advances)
The classic breadth-momentum gauge: the 19-day EMA of net advances minus the 39-day EMA, computed across eligible US-listed common shares. Positive = participation accelerating; negative = decelerating. Zero-line crosses, extremes, and divergences against SPY are the signals — and a negative reading is one of the four Hindenburg Omen criteria. Below the headline series, the same pair is drawn for today's S&P 500 members, today's Nasdaq-100 members and all Nasdaq-listed stocks.
Today's reading
As of market close on October 19, 2026, the McClellan Oscillator is -14.39 — short-term breadth (19-day EMA of net advances) is lagging intermediate breadth (39-day EMA) across eligible US-listed common shares. The oscillator fell 2.8 points from the prior session. The series runs from 2016 to present.
Sources, methodology & freshnessDaily net advances across eligible US common stocks (several thousand in a session; available history) · Daily after market close (~1:30 PM PT)Data as of 2026-10-19 · Open ↓Close ↑
Short-term breadth is lagging intermediate breadth.
SPY closed at $766.48. A negative oscillator is one of the four Hindenburg Omen criteria.
By universe, 2026-10-19
The Nasdaq-100 members' oscillator is positive (+9.7) while the all-Nasdaq-listed one is negative (-26.9): breadth momentum among the largest Nasdaq companies is moving the other way from the rest of the exchange.
Oscillator by universe
All US Stocks: McClellan Oscillator
EMA19 − EMA39 of ratio-adjusted net advances, RANA = 1000 × (advances − declines) ÷ (advances + declines), across every eligible US-listed common share, with SPY overlaid. Ratio adjustment keeps a reading in 2017 comparable to one today while the number of stocks changes. Judge extremes against this series' own history (±60 marks stretch) rather than classic NYSE thresholds. This is the series the Hindenburg Omen reads.
S&P 500 Members: McClellan Oscillator
The same oscillator on today's S&P 500 members (493 of 503 have price history; list as of 2026-10-19). The oscillator subtracts one average of the daily readings from another, so a steady upward tilt in old readings mostly cancels out. Survivorship moves this chart far less than the summation index below.
Nasdaq-100 Members: McClellan Oscillator
The same oscillator on today's Nasdaq-100 members (98 of 101 have price history), with QQQ overlaid. With about a hundred votes a session, each stock moves the reading more than in the broader universes, so swings run wider.
All Nasdaq-Listed Stocks: McClellan Oscillator
Every eligible common share listed on Nasdaq, with QQQ overlaid. Most are small companies, so this shows the breadth beneath the Nasdaq-100. It keeps stocks that later delisted and carries none of the index versions' survivorship tilt. When it falls while the Nasdaq-100 version rises, the gains are concentrated in the largest names.
Summation index by universe
All US Stocks: McClellan Summation Index
The running total of the oscillator, the same construction StockCharts publishes as NYSI, computed on every eligible US common share. Because the universe differs from the NYSE composite, it will not match $NYSI. It accumulates from the first covered session, so its starting level is arbitrary: read its direction, its zero crossings and its divergences against price, and leave the absolute value aside.
S&P 500 Members: McClellan Summation Index
The running total of the S&P 500 members' oscillator above. Its level carries the survivorship tilt described below.
Nasdaq-100 Members: McClellan Summation Index
The running total of the Nasdaq-100 members' oscillator above, with QQQ overlaid.
Survivorship caveat. The S&P 500 and Nasdaq-100 versions use today's members all the way back to 2016-12-27; we hold no historical membership. Companies removed from either index, often after falling, are missing, and later additions are counted before they joined. Their older daily readings are therefore tilted upward, which lifts the summation index's level. Across the whole record the S&P 500 members' summation averaged 598 points above the all-stocks line and the Nasdaq-100 members' 1,202 points above it. Part of that gap is survivorship and part is how large companies actually traded, and this data cannot separate the two. Read these lines for turns and divergences, and leave their levels against the all-stocks line aside. Signal studies on this site use the all-stocks series only.
All Nasdaq-Listed Stocks: McClellan Summation Index
The running total of the all-Nasdaq-listed oscillator, our analogue of $NASI. $NASI counts every Nasdaq issue, including funds, preferreds and warrants; this counts common stocks only, so the two will not match. The advance-decline lines for all four universes are on the A-D Line page.
Reading the current tape
As of 2026-10-19, the McClellan Oscillator stands at -14.39 — breadth momentum is negative (short-term participation decelerating), with SPY at $766.48. The oscillator fell 2.8 points on the session.
Short-term breadth is lagging intermediate breadth.
SPY closed at $766.48. A negative oscillator is one of the four Hindenburg Omen criteria.
How McClellan Oscillator Works
- 1Start from daily net advancesEach session we count advancing minus declining eligible US common stocks — several thousand in a current session — using the same series that drives the advance-decline line.
- 2Smooth with two exponential moving averagesEach day's count is ratio-adjusted: 1000 × (advances − declines) ÷ (advances + declines), so readings stay comparable as the number of stocks changes. The oscillator is the 19-day EMA of that figure minus the 39-day EMA. Both EMAs warm up over their full period (seeded with the SMA) before the oscillator prints, so early values are never seed-dominated.
- 3Read it as breadth momentumPositive = short-term breadth running ahead of intermediate breadth (acceleration); negative = deceleration. Zero-line crosses mark momentum regime changes; extremes mark exhaustion.
- 4Watch divergences and the zero lineA rising index with a falling oscillator means each push is coming on weaker participation. A deeply negative oscillator that turns up before price does is the classic early-bottom tell. The oscillator is also criterion #3 of the Hindenburg Omen (must be negative).