Post-Market Change % (Anchored)

A custom indicator created by TrendSpider Team on TrendSpider. You can import this custom indicator into your TrendSpider account. Don't have TrendSpider? Create an account first, then import the custom indicator.

This indicator paints the change from closing price of the day to enable traders to find movers in post market.

Source code

This indicator had been implemented by TrendSpider Team in JavaScript on TrendSpider. Check out the developer documentation to learn more about JS on TrendSpider.

// This indicator was made by AI and has not been QA checked by the TrendSpider development team. The indicator is for informational purposes only.
describe_indicator('Post-Market Change % (Anchored)', 'lower', { shortName: 'PostM Change%', decimals: 'by_symbol_2x' });

// Define the pre-market open time (4:00 AM EST)
const preMarketOpenHour = 16;

// Series to store the percentage change from 4:00 AM open
const percentChangeSeries = series_of(null);

// Function to calculate percentage change
function calculatePercentageChange(currentPrice, openPrice) {
    return ((currentPrice - openPrice) / openPrice) * 100;
}

// Variables to track the pre-market open price and current day
let preMarketOpenPrice = null;
let anchorCandleFound = false; // To ensure the anchor is set correctly
let currentDay = null;

// Loop through all candles and calculate the percentage change from 4:00 AM open
for (let i = 0; i < time.length; i++) {
    const date = time_of(time[i]);
    const day = date.dayOfYear;

    // Reset at the start of each new day
    if (day !== currentDay) {
        currentDay = day;
        preMarketOpenPrice = null;
        anchorCandleFound = false; // Reset anchor flag for the new day
    }

    // Set the pre-market open price when the first candle at or after 4:00 AM appears
    if (!anchorCandleFound && date.hours >= preMarketOpenHour) {
        preMarketOpenPrice = close[i]; // Set pre-market open price
        anchorCandleFound = true; // Anchor found, no need to check further
    }

    // Calculate and store the percentage change if the pre-market open price is set
    if (preMarketOpenPrice !== null) {
        percentChangeSeries[i] = calculatePercentageChange(close[i], preMarketOpenPrice);
    } else {
        percentChangeSeries[i] = null; // No percentage change before 4:00 AM
    }
}

// Paint the percentage change as a line plot
paint(percentChangeSeries, { name: 'PostM Change %', color: '#ff0000', thickness: 2, style: 'line' });

// Paint a horizontal line at 0% level
paint(horizontal_line(0), 'Zero Level', 'black');