Momentum investing sounds great during a bull run. But the strategy has a specific, well-documented crash behaviour at market reversals. Here is how it works, how the index is built, and why trailing returns are the worst reason to enter.
Momentum investing is simple: you buy what has been going up, on the theory that it will keep going up. The Nifty 500 Momentum 50 index formalises this — it selects the 50 stocks from the Nifty 500 with the strongest recent price momentum and rebalances them every six months. But momentum has a specific failure mode: when the market reverses direction, momentum funds get hit harder than the broader market. Every bull-market article about momentum funds leads with returns. This one leads with the mechanics and the risk — so you understand what you are actually buying.
What momentum means as a factor
Momentum is one of the most studied factors in finance. The academic evidence, going back to Jegadeesh and Titman's 1993 paper, shows that stocks that have performed well over the past 6-12 months tend to continue performing well over the next 3-12 months. The effect has been documented across markets, time periods, and asset classes.
The behavioural explanation: investors under-react to good news initially, then over-react as the trend becomes obvious. Prices drift upward in a gradual trend that momentum strategies capture.
The catch — and every momentum investor needs to understand this — is that momentum also has a well-documented crash risk. At market inflection points, when the trend reverses sharply, momentum portfolios are loaded with the very stocks that are now falling fastest. The strategy that profited from the trend now amplifies the reversal.
How the Nifty 500 Momentum 50 index is built
The index construction is transparent:
1. Universe: Nifty 500 stocks. 2. Selection: Stocks are ranked on a composite momentum score based on 6-month and 12-month price returns, adjusted for volatility. The top 50 stocks by this score are selected. 3. Weighing: Market-cap weighted, with individual stock caps. 4. Rebalancing: Semi-annually (June and December).
The key detail: rebalancing happens only twice a year. If a stock's momentum changes dramatically between rebalances, the index does not react. It holds the stock until the next scheduled rebalance, regardless of what is happening to its price. This is by design — momentum is a medium-term signal, not a daily one — but it means the index can be holding stocks that lost momentum months ago.
Index drawdown behaviour — the honest section
Momentum indices have shown characteristic crash behaviour at market reversals. When the broad market turns down sharply after a sustained rally, momentum indices loaded with high-flying stocks can fall significantly more than the parent index.
Based on historical index data from NSE:
| Period | Nifty 500 Drawdown | Nifty 500 Momentum 50 Drawdown | |---|---|---| | COVID crash (Feb-Mar 2020) | -38% | -42% | | Russia-Ukraine correction (2022) | -18% | -24% | | Mid-cap sell-off (Jan-Mar 2018) | -15% | -21% |
At every major market reversal in the available data, the momentum index underperformed the parent index on the downside. The magnitude of underperformance ranges from 3-6 percentage points — consistent with the academic literature on momentum crashes.
This does not mean momentum funds are a bad investment. It means their risk is not the same as a broad-market index fund. You are being paid for bearing momentum crash risk. If you are not aware of that risk when you buy, you will discover it at the worst possible time.
Active momentum funds vs momentum index funds
There are now both active momentum funds (fund managers using momentum as one factor among many) and passive momentum index funds (tracking the Nifty 500 Momentum 50 or similar). The difference matters:
| | Active Momentum Funds | Passive Momentum Index Funds | |---|---|---| | Strategy | Fund manager discretion, may combine momentum with quality, growth, or other factors | Rules-based, tracking a published index | | Expense ratio | Higher (0.8-1.2%) | Lower (0.2-0.5%) | | Turnover | Variable, depends on the fund manager's process | Fixed around semi-annual rebalancing | | Tracking error | Not applicable | Low, by design | | Risk of style drift | Yes — manager may reduce momentum exposure during drawdowns | No — the index mandate is mechanical |
The passive index fund gives you pure, undiluted momentum exposure — and pure, undiluted momentum crash risk. An active fund may or may not reduce exposure during drawdowns, depending on the fund manager's process. This is not necessarily better — you are paying higher fees for the fund manager's judgement, which may or may not add value.
Why trailing returns are exactly the wrong reason to enter
Momentum funds have delivered strong trailing returns in the 3-5 year period ending June 2026 — the broad market has been rising, and momentum strategies have captured that trend. A 3-year trailing return of 20%+ in a momentum fund looks great on a factsheet.
But if you buy a momentum fund because its 3-year returns are high, you are buying a strategy that has already profited from the trend. You are entering after the trend has delivered its returns, and you will bear the full crash risk if and when the trend reverses.
This is not a prediction that a crash is imminent. It is a statement about the logic of buying momentum: the best time to buy momentum is when recent returns have been poor, because that is when the strategy is unloved and cheap. The worst time is when recent returns have been spectacular, because that is when the strategy is loaded with stocks at their peak momentum.
Where momentum fits in a portfolio
Momentum should be a satellite allocation, not a core holding. Reasonable allocations for an investor who understands the risk:
- 10-15% of the equity portfolio in a momentum fund, with the remaining 85-90% in a diversified equity fund (flexi cap, index, or large cap). - Horizon of 7+ years — momentum crashes can take time to recover from. - SIP rather than lumpsum — spreading your entry across time reduces the risk of deploying a large sum at a momentum peak.
Do not make a momentum fund your only equity holding. The strategy is not a substitute for broad market exposure.
Taxation and turnover cost
Momentum funds generate higher turnover than a typical index fund because of the semi-annual rebalancing — approximately 80-120% annual portfolio turnover, depending on the index version and market conditions. This has two implications:
1. Capital gains distributions: Frequent rebalancing means the fund realises capital gains more often, which are distributed to unitholders (in the growth option, this reflects in the NAV rather than as a cash payout). 2. Transaction costs: Higher turnover means higher brokerage, STT, and impact costs, which reduce net returns. The expense ratio covers management fees but not all transaction costs — some are borne by the fund's NAV.
The tax treatment is the same as any equity fund: - STCG (≤12 months): 20%. - LTCG (>12 months): 12.5% on gains above Rs 1,25,000 per financial year.
Frequently Asked Questions
### What is a momentum fund? A momentum fund invests in stocks that have shown strong recent price performance, based on the theory that upward price trends tend to persist in the medium term (6-12 months). In India, most momentum funds track or are based on the Nifty 500 Momentum 50 index.
### Are momentum funds risky? Yes — more volatile than a broad-market index fund. Momentum strategies have a documented crash risk at market reversals, historically underperforming the parent index by 3-6 percentage points during major drawdowns.
### Should I invest in an active momentum fund or an index momentum fund? An index fund gives you pure momentum exposure at low cost but with zero protection during drawdowns. An active fund may or may not reduce drawdowns, depending on the fund manager — at higher cost. If you want pure factor exposure, choose the index. If you want human judgement around the factor, choose active — but verify the fund manager's actual behaviour during previous drawdowns.
### Is now a good time to invest in a momentum fund? This article does not make market-timing recommendations. The logical principle: momentum funds are most attractive when trailing returns have been poor (unloved) and most dangerous when trailing returns have been spectacular (loaded at the peak). Use SIPs to spread entry over time.
### How much of my portfolio should be in momentum funds? As a satellite allocation: 10-15% of your equity portfolio. Not a core holding and not your only equity fund.
### How does taxation work for momentum funds? Same as any equity fund. STCG at 20% (held ≤12 months). LTCG at 12.5% on gains above Rs 1,25,000 (held >12 months). Higher turnover means more frequent capital gains realisations, which can affect post-tax returns.
Disclaimer
This article is for educational purposes only. It does not recommend any specific fund or investment strategy. No fund named in this article is recommended. Past performance, including index drawdown data cited, does not guarantee future results. Mutual fund investments are subject to market risks. Read all scheme-related documents carefully before investing.