Zerodha made ₹4,700 crore in profit in FY24. For context, that's more than many mid-cap listed companies on the NSE. They charge ₹0 for buying and holding stocks. So either Nithin Kamath is running a charity, or "free" is doing a lot of heavy lifting in that sentence.
It's the second one. Discount brokers have built some of the most profitable financial businesses in India, and the model is elegant: remove the obvious fee, then earn from five other places the customer isn't watching. This isn't a complaint — it's a map. Once you understand where the money flows, you can make smarter decisions about how you trade.
The ₹20 Flat Fee Is More Than It Looks
Zerodha's flagship pitch is ₹20 per executed order for intraday equity, F&O, and currency. Sounds small. It isn't.
Think about what ₹20 per order means at scale. Zerodha has processed over 10 million active clients. Even if each client fires off just 4–5 intraday orders a month, you're talking crores in daily brokerage revenue just from the flat fee. The model works precisely because it feels cheap. A trader paying ₹20 instead of 0.5% on a ₹1 lakh order is saving ₹480. But that trader often places far more orders because the entry cost feels low — and each of those orders generates another ₹20.
This is the first incentive baked into the structure: flat fees reward high-frequency trading behaviour. The broker earns more when you trade more, even if each trade costs you less.
F&O Is Where the Real Money Sits
If equity intraday is the entry drug, F&O is the revenue engine. The average F&O trader in India pays approximately ₹1,800 per month in brokerage alone — before STT, exchange fees, GST, and SEBI turnover charges stack on top.
F&O volumes on NSE are staggering. India is now the world's largest derivatives market by contract volume. Every one of those contracts goes through a broker. At ₹20 per leg — entry and exit — a single round trip on a Nifty options trade costs ₹40 in brokerage. Do that 20 times in a month and you've handed your broker ₹800, just for the clicks.
Zerodha's Kite platform, Groww's trading interface, and Upstox's interface are all built to make options trading frictionless. One-click order placement, visual option chains, real-time greeks. That design investment isn't for your benefit — it's to reduce the friction between you and placing another order. The more seamless the interface, the more trades happen, the more ₹20 fees accumulate.
Your Idle Cash Is an Asset — Theirs, Not Yours
Here's the line that most traders completely miss: float income.
When you transfer ₹50,000 into your Zerodha or Groww account and it sits there for a few days before you deploy it, that money doesn't sit in a zero-yield vault. Brokers pool client funds and park them in overnight money market instruments, liquid mutual funds, or earn interest via clearing corporation mechanisms. The going rate is roughly 7–8% annualised.
On aggregate, even if the average active client keeps ₹20,000 idle in their trading account, across millions of clients that's thousands of crores sitting and spinning. At 7% per year, ₹10,000 crore in idle float generates ₹700 crore annually — without a single trade being placed.
This is why you'll notice that fund withdrawal timelines are never instant. Technically the money is yours, but operationally, every extra hour it stays in the account is earning the broker a few paise per rupee per day.
Mutual Fund Platforms and the Trail Commission Game
Groww started as a mutual fund platform before it added stocks and F&O. That origin matters, because mutual funds are where a different revenue model runs quietly in the background.
Direct plans on SEBI's mandate don't pay distributors. But platforms like Groww and Zerodha's Coin do earn in adjacent ways. Coin charges ₹50 per month (capped) for holding mutual funds in demat form — a small but recurring charge at scale. Some platforms also offer regular plans through partner arrangements where trail commissions flow back to the platform, typically 0.5–1% of AUM annually.
At ₹10,000 crore of MF AUM on a platform — a number Groww crossed a few years back — even 0.5% trail is ₹500 crore in annual income. That's pure recurring revenue, no trading required, just clients staying invested.
Payment gateway charges are another quiet earner. When you add money to your trading account via UPI or net banking, the platform absorbs the payment gateway cost. But when you make certain types of transactions — IPO applications through ASBA, some AMC purchases — there are processing fees that flow back.
Margin and Interest: The Lending Angle
The most direct lending product discount brokers run is margin funding. If you want to buy ₹2 lakh worth of stocks but only have ₹1 lakh, some brokers will lend you the rest against your existing holdings as collateral. The interest rate on this ranges from 12–18% per annum depending on the broker and product.
This is a fully regulated activity under SEBI's margin pledge framework. It's also very profitable. The broker borrows cheap (from the float, from NBFCs, or from their own balance sheet) and lends to you at a spread. The risk sits with you — if the stock falls and breaches margin, your position gets squared off automatically.
Zerodha has been more conservative about margin lending than some competitors. But the incentive is there, and smaller discount brokers lean on it harder. Every "buy more than you have" feature you see on a trading app is a doorway to a 15%-interest product.
What This Means for How You Should Trade
None of this is hidden — it's just not advertised prominently. SEBI regulations require brokers to disclose their revenue streams, and Zerodha's annual reports are public. The ₹4,700 crore profit figure is straight from their FY24 filing.
The useful takeaway is this: broker interfaces are not neutral tools. They are built around revenue lines. F&O is easy to trade because F&O is profitable for the broker. Idle cash warnings are rare because idle cash is profitable for the broker. One-click leveraged positions exist because margin interest is profitable for the broker.
That doesn't make these platforms bad. Zerodha genuinely democratised trading in India. ₹20 flat is better than 0.5% of turnover for anyone trading more than ₹4,000 at a time. Groww brought mutual fund investing to people who'd never opened a demat account.
But when you're deciding how much cash to keep in your trading account, whether to trade F&O that often, or whether to use margin — you're making a choice that directly affects your broker's P&L in a specific, calculable way. Keep your idle cash in a liquid fund linked to your bank, not sitting in your trading account. Pull out capital you're not deploying within 2–3 days. And if you're paying ₹1,800 a month in brokerage on F&O, run that number against your actual monthly P&L before you place the next order.
The broker already ran those numbers. You should too.