Elder Ray Index: Bull Power and Bear Power for Nifty Traders

What the Elder Ray Index actually measures

The Elder Ray Index was created by Dr Alexander Elder and explained in his 1993 book Trading for a Living. The idea is simple but powerful. The 13-day exponential moving average (EMA) represents the market's consensus on fair value. The day's high shows how far buyers could push price above that consensus, and the day's low shows how far sellers could drag it below. Elder called the first force Bull Power and the second Bear Power.

Because the EMA is a moving line, both values change every day. Bull Power is almost always positive in an uptrend and Bear Power is almost always negative. What matters is not the raw sign but the trend in those numbers. Bears losing their grip (Bear Power rising toward zero even as price falls) often signals an exhausted decline before any moving average crossover confirms it.

On Indian instruments such as the Nifty 50, Bank Nifty or a liquid single stock like Reliance, the Elder Ray works the same way mechanically, but the typical magnitude differs. Bank Nifty, which moves in hundreds of points, will show far larger Bull and Bear Power values than a Rs 1,500 stock. You read the indicator relative to the instrument's own history, never against a fixed rupee threshold.

The two formulas, written out

There are only two calculations, and both lean on the same 13-day EMA of the closing price. You compute the EMA first, then subtract it from the high and the low of the same session.

• Bull Power = Today's High minus 13-day EMA of Close
• Bear Power = Today's Low minus 13-day EMA of Close
• The 13-day EMA itself uses a smoothing factor of 2 divided by (13 plus 1), which equals 0.1429, applied to each new close.

Most platforms plot Bull Power and Bear Power as two separate histograms below the price chart. You do not have to calculate them by hand. But knowing the arithmetic lets you sanity-check what your charting tool shows, and it makes the worked example below transparent rather than a black box.

Worked example: a dated Nifty 50 Bull and Bear Power case

Let us replace the vague textbook case with realistic Nifty 50 daily figures. Assume that over a recent two-week stretch the Nifty drifts down from about 24,800 toward 24,300, and the 13-day EMA settles near 24,520. The numbers below are illustrative and rounded to whole points so the arithmetic is easy to follow.

Read the Bear Power column carefully. Price makes its lowest low on Day 3 (24,330) and a roughly equal low on Day 4 (24,360). But Bear Power improves from -190 on Day 3 to -140 on Day 4 and then to -70 on Day 5. Sellers pushed price almost as low, yet they could no longer drag it as far below the EMA. That is a classic bullish Bear Power divergence: price flat to lower, Bear Power higher. Elder rated this as one of the strongest buy setups the indicator produces.

Meanwhile Bull Power never turned negative across the week, telling you buyers were still able to lift price above the consensus value each day. The combination, fading bear pressure plus persistent bull pressure, is your signal to look for a long entry on Day 5's close around 24,500, with a stop below the 24,330 swing low. This is a far more reliable reading than the old shortcut of waiting for Bull Power to merely cross above zero.

Turning the signal into a sized Nifty options trade

A signal is worthless until you size it and count the costs. Suppose that Day 5 divergence convinces you the Nifty will bounce, and you buy one lot of a weekly 24,500 call expiring the coming Tuesday. The Nifty F&O lot size is 65. Assume the call is trading at a premium of Rs 120 when you enter.

• Premium paid = 120 multiplied by 75 = Rs 9,000 (this is your maximum risk on a long option).
• The bounce plays out and two days later the Nifty trades near 24,750, lifting the call premium to Rs 230.
• Premium received on exit = 230 multiplied by 75 = Rs 17,250.
• Gross profit before costs = 17,250 minus 9,000 = Rs 8,250.

Now subtract the real charges, because the gross figure flatters you. On the buy side there is brokerage (a discount broker typically charges a flat Rs 20 per order), plus exchange transaction charges and 18 percent GST on brokerage and exchange charges. On the sell side you also pay Securities Transaction Tax. STT on the sell side of an options trade is 0.15 percent of the premium value (this is the rate effective since 1 April 2026, raised from the 0.10 percent that applied from October 2024). There is also SEBI turnover fees and stamp duty, both tiny.

Net profit is roughly 8,250 minus 97, or about Rs 8,153 on this single lot. The costs are small here because long-option premiums are modest, but they scale up fast when you trade many lots or sell options (where STT and turnover charges bite harder). Always model charges before deciding a setup is worth taking. These figures are illustrative; your exact charges depend on your broker and the live premium.

How this profit is taxed in India

This is where many new Indian traders trip up. Profit from trading futures and options is treated as business income, not as capital gains. So the roughly Rs 8,162 above is added to your other business and salary income and taxed at your applicable income-tax slab rate. There is no flat 15 or 20 percent rate for F&O, and STT paid is allowed as a business expense.

Capital gains rates only apply if you instead buy and hold the underlying shares in the cash market. For equity delivery, short-term capital gains (held under 12 months) are taxed at 20 percent and long-term capital gains are taxed at 12.5 percent on the amount above Rs 1.25 lakh per year. These cash-market rates do not touch your options trade, but they matter the moment you switch from trading the index to investing in a stock like HDFC Bank or TCS.

Choosing the EMA length for Indian instruments

The default is a 13-day EMA, and it works well on daily Nifty and Bank Nifty charts. But the right length depends on your holding period and on how volatile the instrument is. Bank Nifty swings far more than the broad Nifty, so its Bull and Bear Power readings are noisier and a slightly longer EMA can smooth out whipsaws.

Do not over-optimise. If you change the EMA until the signal looks perfect on past data, you are curve-fitting and the edge will vanish in live trading. Pick one setting that matches your timeframe, then judge it across dozens of real trades in your journal before tweaking.

Combining Elder Ray with other tools

Elder himself designed the Elder Ray as one screen in his three-screen system, never as a standalone trigger. The first screen is the longer-term trend (often a weekly EMA), the second is the Elder Ray or another oscillator, and the third is the entry technique. The point is that you only take Elder Ray buy signals when the bigger trend already points up.

• Pair with the 13-day EMA slope: only act on bullish Bear Power divergence when the EMA itself is rising or flat, never when it is falling steeply.
• Confirm with RSI: a bullish Bear Power divergence that lines up with RSI rising out of oversold near 30 is a higher-quality long.
• Watch volume: on single stocks like Reliance or Infosys, a divergence backed by rising volume on the up-day is more trustworthy than one on thin volume.
• Use MACD for trend strength so you avoid taking Elder Ray longs into a strong downtrend.

Never stack five indicators that all say the same thing. Two or three tools that measure different aspects (trend, momentum, and pressure) give genuine confirmation. Elder Ray measures pressure, RSI measures momentum, and the EMA measures trend, so together they cover real, non-overlapping ground.

Limitations and false signals in Indian markets

The Elder Ray is a lagging-plus-leading hybrid: the EMA lags, the high and low are current. In a tight, sideways Nifty range, Bull and Bear Power oscillate around zero and throw off frequent, low-quality crossovers. This is exactly when divergence discipline matters most, because most random zero-crosses in a range are noise.

Indian markets also gap. Around the RBI policy, the Union Budget, US Fed decisions, or a heavy expiry day, the Nifty and especially Bank Nifty can open far from the previous close. A single gap distorts the day's high or low and can spike Bull or Bear Power in a way that does not reflect steady pressure. Treat readings on event days with caution and lean on your stop-loss rather than the indicator.

• Avoid acting on Elder Ray signals in the final 30 minutes before a major event result.
• On weekly expiry days, options premiums decay fast; a correct directional read can still lose money to time decay if you are slow.
• Always place a hard stop. The Elder Ray tells you about pressure, not about how much you can afford to lose.

A practical checklist before you trade an Elder Ray signal

Bring the whole page together into a routine you can repeat. The goal is to act only on high-quality divergence signals that survive both a trend filter and a cost check.

• Is the 13-day EMA rising or flat (for a long) or falling or flat (for a short)?
• Does Bear Power make a higher low while price makes an equal or lower low (bullish divergence)? Or the mirror for shorts?
• Does a second tool such as RSI or volume agree?
• Have you sized the position to the correct lot (Nifty 75, Bank Nifty 15, FinNifty 25, Sensex 10)?
• Have you netted brokerage, STT and GST so you know your true breakeven?
• Is there a hard stop in place, and have you logged the trade with its date and reason?

Sources and further reading

For authoritative data and further reading, see Zerodha Varsity, Investopedia and NSE India. Always confirm current lot sizes, STT rates, brokerage and contract specifications on the official source before you trade. You can also revisit the RSI guide to pair momentum with Elder Ray pressure readings.

Sources and Further Reading

For authoritative data and further reading on this topic, refer to Zerodha Varsity, Investopedia and NSE India. Always confirm current rules, rates and contract specifications on the official source before you trade.