Price action reveals market psychology across trading sessions Figure 27.1 , Price action reveals market psychology across trading sessions

A Candlestick Chart encodes four price dimensions per time period , open, high, low, close (OHLC) , into a single glyph. The real body spans the open-to-close range and is the primary signal: its height encodes price conviction, its colour encodes direction. The wicks (upper and lower shadows) extend to the session's extremes, encoding the full range of price exploration. This is a glyph chart , a composite mark that packs four quantitative values into one symbol.

The message is about market psychology across sessions , not a single price level, not a trend line, not a distribution. The viewer needs to see conviction (body height), direction (colour), and range exploration (wick length) simultaneously. No single-dimension chart can deliver all four OHLC values. A line chart collapses to close price only, discarding 75 percent of the available information. A simple OHLC bar chart encodes the same data but is perceptually harder to parse at density.

A line chart on closing price , the most common alternative , discards open, high, and low entirely. The viewer loses all information about intra-session volatility, gap openings, and the relationship between opening conviction and closing outcome. A session that opened high, sold off dramatically, but recovered to close flat appears identical to a calm session that never moved. A Box Plot , visually similar , encodes statistical distribution (quartiles, median) across many observations . A candlestick encodes four specific price events within one time period.

Paste this into Claude Code to generate a working version of this chart, plus its data file. The result will not be a perfect replica , the goal is that the reader can run the prompt, get a chart of this type, and read its source. Generate a complete, self-contained candlestick chart in D3 v7. Two files:

The ideas in this chapter didn't appear from nowhere. Charles Dow co-founded The Wall Street Journal and developed the first stock-market index in 1896 , and the OHLC bar that would later evolve into the candlestick was central to how he taught readers to read price action. Charles Dow, circa 1890. AI-generated portrait based on a public domain photograph (Wikimedia Commons).

The ideas in this chapter didn't appear from nowhere. Charles Dow co-founded The Wall Street Journal and developed the first stock-market index in 1896 , and the OHLC bar that would later evolve into the candlestick was central to how he taught readers to read price action. Charles Dow, circa 1890. AI-generated portrait based on a public domain photograph (Wikimedia Commons).