Side-by-side white lines: the twin-candle gap continuation

Side-by-side white lines are two white candles of similar size that open at about the same price, standing next to each other on the far side of a gap. When the pair sits above the gap, the pattern is called the upside gap side-by-side white lines and is read as bullish continuation. When the pair sits below a gap in a decline, it is the downside gap side-by-side white lines, which tradition treats, perhaps surprisingly, as bearish continuation even though both candles are white.

The pair is the point. A single white candle after a gap could be a one-off. Two that open at the same level and close at similar heights show the market accepting the new price area for a second session in a row. Nison counts the upside version among the "window" patterns that confirm a gap. The downside version is rarer, and its two white candles are usually read as short covering rather than real buying.

There is also a Finabase-specific detail to clear up first: in the app, this pattern's chart markers are labeled "Evening Star". That label is inherited from the legacy app and is kept for compatibility; the detector behind it is TA-Lib's CDLGAPSIDESIDEWHITE, not the evening star. This page explains the pattern, the rules, two real cases and the record of 63 detections.

Anatomy of side-by-side white lines

The upside version in three steps:

1. A candle in an advance, which defines the bottom edge of the coming gap.
2. The first white line. It gaps up so that its whole body is above the prior body.
3. The second white line. It opens at about the same price as the first white line, closes at about the same height, and its body also stays above the first candle's body. The gap is untouched by either body.

For the downside version, the first candle sits above, the gap is downward, and the two white candles stand below it with matching opens. They close higher than they open, but neither climbs back into the gap.

The exact rules Finabase uses

Finabase runs TA-Lib's CDLGAPSIDESIDEWHITE on daily bars. "Near" is 20% and "equal" is 5% of the average high–low range of the five candles before the first white line.

Notes on the code:

The window must stay open for both lines. TA-Lib checks the gap from the first body to each white body separately, which is how it enforces the textbook's "the second line does not close the window". Shadows are ignored, so the second white candle may wick into the gap as long as its body does not.

"Same open" is tight. At 5% of the recent average range, a stock moving $2 a day must open the two white lines within about 10 cents of each other.

No trend test. In our sample 32.7% of upside detections came after a ten-session decline, outside the continuation setting the pattern is named for.

Why two matching white candles matter

A gap up is an opinion: buyers decided overnight that the stock was worth more than the whole previous range. The first white candle confirms the opinion for one day. The second white line, opening right where the first one did, is the market returning to the same starting price and buying again. It shows there was no rush to sell back into the gap and that demand at the new level was repeatable.

The downside version is the puzzling one. After a gap down, two white candles look like buying. The traditional reading is that they are weak bounces: they open at the same depressed level, rise modestly, and never reach the gap. Holders who wanted out are using the bounces to sell, and the gap overhead acts as resistance. Whether that reading holds is exactly what our small sample cannot tell.

Confirmation

• Upside: a close above the higher of the two white candles' highs.
• Downside: a close below the lower of the two white candles' lows.
• The gap holds on any retest; a close back inside the window weakens the case.
• Trend alignment: the gap should be in the direction of the existing trend, which a moving average or the Relative Strength Index (RSI): how to read and use it can help confirm.

Two real cases

Caterpillar, January 14, 2026. CAT closed at $629.77 on January 12. On January 13 it gapped up to open at $633.20 and closed at $636.53. On January 14 it opened 90 cents away at $634.10 and closed at $638.75; the bodies were $3.33 and $4.65, inside TA-Lib's "near" allowance. The second white line dipped intraday to $623.07, deep into the gap, but its body stayed above it. That same bar also triggered TA-Lib's advance block (−100) and hammer (+100), so the chart carried three conflicting labels at once. The next close was $647.18, confirming the continuation, and ten sessions later the stock was 4.1% higher.

Intel, March 7, 2025. INTC had fallen 17.0% in ten sessions. After a black candle that closed at $20.81 on March 5, it opened below that body on March 6 at $20.26 and closed at $20.75, then opened at $20.27 on March 7 and closed at $20.64: two small white lines below the gap, a textbook downside version. The next session closed lower, at $19.93, which confirmed the pattern. Days later, on March 12, Intel named a new chief executive and the stock jumped. Ten sessions after the pattern it was 17.5% higher. A continuation pattern can't anticipate company news, and a stop above the gap would have limited the damage.

What the data says

CDLGAPSIDESIDEWHITE fired 63 times on 44 of the 60 large US stocks and ETFs over two years of daily bars (October 30, 2024 to October 29, 2026): 52 upside and 11 downside.

• Upside: a small tilt. 55.8% higher after five sessions against 53.1%, and a ten-session average of +1.04% against +0.66%. The confirmed subset did not improve on it.
• Downside: the opposite of the textbook, on 11 cases. Nine of the eleven were not lower a week later, Intel among them. With so few cases this says more about a rebounding market than about the pattern.

How it compares with other gap patterns

The last row is there because of the label. A true evening star is a three-candle bearish reversal with a long black third candle. Side-by-side white lines have no black candle at all, and the upside version is bullish.

An educational outline

How traders commonly use the pattern. It isn't a recommendation to trade.

1. Check the direction of the trend and the gap. Upside white lines after an advance are the classic case; the downside version is rare and contested.
2. Mark the window. The top of the first candle's body (upside) is the level that should not be closed on a closing basis.
3. Wait for a breakout close beyond the white lines' range.
4. Respect the hidden conflicts. As at Caterpillar, other patterns may fire on the same bar; read the candle, not the label.

How Finabase shows side-by-side white lines

• Chart markers, labeled "Evening Star". In Finabase, the study and its markers for CDLGAPSIDESIDEWHITE carry the name Evening Star. This is a copy-paste label from the legacy app that Finabase keeps for compatibility. The detection itself is the side-by-side white lines described here; the study's chart class is CdlgapsidesidewhiteChart.
• Scanner. Upside cases (+100) appear on the bullish list, and downside cases (−100) on the bearish list, where the latest candle on the chart will be white.
• Signals tab. On a symbol page such as AAPL's signals, the Candlestick gauge counts this pattern's most recent reading in the last eight bars as one of 61 votes: Buy for upside, Sell for downside. The score (buy − sell) / (buy + sell + min(neutral, max(buy, sell))) reads Strong Sell below −0.6, Sell below −0.2, Neutral below 0.2, Buy below 0.6 and Strong Buy above.

Frequently asked questions

Why does Finabase call this pattern "Evening Star"?

It is a legacy label carried over from the original app and kept for compatibility. The markers are produced by TA-Lib's side-by-side white lines detector. The genuine evening star (CDLEVENINGSTAR) is a separate study that is also named "Evening Star", but Finabase runs it with a penetration setting of 10 inherited from the legacy app, and at that setting it did not fire once in our 29,760-bar sample. In practice, an "Evening Star" marker you see on a Finabase chart today almost certainly comes from this side-by-side white lines detector.

Can the downside version really be bearish with two white candles?

That is the traditional reading: the white candles are weak bounces that fail to reach the gap. TA-Lib scores it −100. In our 11 cases it mostly preceded gains, which is too few to settle the question.

Is there a black version?

Tradition describes side-by-side black lines too, but TA-Lib has no function for them, so Finabase does not detect them.

What breaks the pattern?

A body that closes back into the window. TA-Lib checks that both white bodies stay clear of the first candle's body.

Summary

Side-by-side white lines are a gap followed by two matching white candles, the market buying at the same new price two days running. The upside version is a continuation signal that showed a small, statistically weak tilt in our data; the downside version is rare, counterintuitive and, on 11 cases, went the wrong way more often than not. In Finabase the markers carry the legacy name "Evening Star", so read the shape on the chart, check the window, and wait for a close beyond the white lines before treating the pattern as anything more than a description.