Hollow candles

Open a modern charting app and you will occasionally meet a candle that seems to contradict itself: it is outlined in red, yet its body is completely hollow - empty inside, the way a green candle usually looks. Or the reverse: a green candle whose body is entirely solid and filled in.

How can a candle be red and hollow at the same time? How can a single day be "down" and "up" at once? The answer is not a glitch. It is a genuinely clever upgrade that packs two separate facts into one candle - and once you see it, you cannot unsee the extra information ordinary candles quietly leave out.

A traditional candlestick compares only two numbers: today's open and today's close. Close above open, it is green; close below open, it is red. That is honest, but it ignores something a holder cares about deeply - yesterday.

Picture a stock that closed at ₹100 yesterday. Awful news breaks overnight, and it gaps down to open at ₹80. Through the day, buyers fight back and lift it to ₹90 by the close. On a normal candlestick chart that candle is bright green, because ₹90 is above the ₹80 open. But anyone holding the stock from yesterday just watched ₹10 evaporate. A cheerful green candle for a real loss feels wrong - and it is, in the one sense that matters to the person holding it.

The hollow candle fixes this by refusing to collapse two different questions into one colour. It separates the interday trend (are we above or below yesterday?) from the intraday battle (did buyers or sellers win the session itself?), and gives each its own visual channel.

This matters most in India around results season. A company beats estimates and gaps up at the open - say from ₹150 to ₹200 - then profit-takers sell into the good news all day and it drifts back to ₹180. On an ordinary candle chart that day is a proud green block, and a newcomer reads pure triumph. The hollow-candle version tells the fuller story at a glance: green, because yesterday's holders are richer, but solid, because everyone who chased the gap at the open is already underwater. Two very different people lived through that 'green' day, and the hollow candle is the only one of the two charts that admits it.

Hollow candles split the information into two independent cues that you read together:

1. Colour (red or green) now depends on today's close versus yesterday's close. This is the trend channel - where you stand against the previous day.
2. Fill (hollow or solid) now depends on today's close versus today's open. This is the momentum channel - who won the day just traded.

Two questions, two answers, one candle. Combine them and you get four types instead of two. Explore all four in the matrix below, and notice how colour and fill can agree or fight.

The two candles where colour and fill disagree are the whole reason hollow candles exist. Here they are side by side, measured against the same prior close.

Put the two channels together and you get four honest states, from strongest to weakest.

1. Hollow green - the best. Closed above yesterday (green) and above today's open (hollow). Both channels agree, up. A clean, powerful advance.
2. Solid red - the worst. Closed below yesterday (red) and below today's open (solid). Both channels agree, down. A clean, powerful decline.
3. Solid green - the gap trap. Closed above yesterday (green) but below today's open (solid). It gapped up in the morning, then sellers pressed it down all day. The trend versus yesterday is still up, but the intraday momentum has died. A green candle that a same-day buyer is losing money on.
4. Hollow red - the intraday recovery. Closed below yesterday (red) but above today's open (hollow). It gapped down, then buyers clawed it back through the session. The trend is still down, but the day itself is turning - the faintest possible hint that sellers are tiring.

The skill is holding both facts at once without letting either one shout down the other.

Which channel should you weight? It depends on your horizon. If you hold for weeks, the colour - where you stand against the recent trend - is the number that matters, and the daily fill is mostly noise. If you are managing a position tightly, the fill - who won today's session - is the earlier warning, because momentum tends to shift before the trend does. The mistake is letting whichever channel happens to be greener capture your attention. The disciplined reader decides in advance which channel their strategy actually depends on, and reads that one first.

Hollow candles add their value in exactly one situation: when the open is far from the previous close - that is, around gaps. So their usefulness rises and falls with how gap-prone the instrument is.

On individual stocks in results season, or on any name exposed to overnight news, hollow candles shine. That is precisely when a day can be 'up on yesterday' and 'down on the open' at once, and the two-channel drawing untangles the contradiction an ordinary candle buries.

On a broad, liquid index, they add little. An index rarely gaps far from its previous close, so the open and the prior close sit close together - and when they do, colour and fill almost always agree. The extra channel is technically present but carries almost no new information; you pay the cognitive tax without receiving the benefit.

Across timeframes the split gets muddier. On a weekly hollow candle, 'yesterday's close' becomes 'last week's close' and 'today's open' becomes 'this week's open' - a gap that now spans a whole weekend of news. The four types still exist, but each summarises a week, so a solid green weekly candle is a far larger warning than a solid green daily one.

And practically: not every platform offers hollow candles, and those that do often bury the setting. If your chart shows only plain green and plain red, the gap-trap information simply is not being drawn for you. Knowing the four types still helps - you can reconstruct them yourself from the close, the open, and the previous close on any day a gap matters.

Hollow candles add a real dimension, but they buy it at a price, and they inherit every limit of the ordinary candle.

They still cannot tell you the order the high and low arrived in - that is deleted on any daily candle, hollow or not. And they add a small cognitive tax: you now decode two variables, colour and fill, instead of one. On a fast-moving chart that extra step can slow you down more than the extra information helps.

More importantly, the green-versus-red colour is a drawing convention about yesterday's close, not a statement about the company. A solid green candle can sit on a genuinely bad day for anyone who bought that morning. The colour records where price stands against an arbitrary reference - the prior close - not what the business is worth.

There is also a quieter failure at the boundary. The fill flips your whole emotional read of a day even when the day was not important. A stock that closes one paisa above its open is 'hollow'; one paisa below is 'solid'. Right at that line, a trivial, meaningless difference in the close decides which of two very different-looking candles you see. Treat fills that sit near the open-close line as the coin-flips they are, not as proof that momentum decisively changed.

The commonest trap is reading a solid green candle as strength simply because it is green. But the solid fill is telling you that everyone who bought at the open is now underwater - the green colour only means the holders from yesterday are still ahead. Green plus solid is a warning dressed as good news.

The trickier case is the hollow red, where two careful readers genuinely diverge.

The repair is the same discipline as always: name what would change your mind before you act. If the next two or three candles close back below their opens and the colour stays red, the intraday buying was noise and the downtrend read holds. No fill pattern is a system that spares you from reading the trend and the risk around it.

Hollow candles fold in the previous day's close without needing any extra line on the chart. But what if you wanted to erase the choppiness of the open and close entirely, and see only the smoothed direction of the trend? That is the first of the noise-filtering charts: Heikin-Ashi.