On March 3, 2026, the DSE posted its worst single-day fall in six years. DSEX shed 108 points in one session and 359 points across the week. In May, the market cap eroded by Tk 9,800 crore over four consecutive losing sessions. Both selloffs began with bad news from somewhere else — Middle East tensions, Fitch’s negative outlook — but the speed of the decline did not come from the news. It came from a mechanic written into the rules of the market itself.
That mechanic is margin trading. And if you have ever wondered why the DSEX can slide 75 points in a single afternoon when the underlying news is no worse than it was at the open, the answer is sitting in a regulation gazetted on November 6, 2025.
Here is what that regulation does, what the 1:0.5 ratio actually means for your buying power, and why one investor’s margin call becomes everyone’s problem.
The 1:0.5 Ratio in Plain Numbers
The BSEC (Margin) Rules, 2025 set the leverage ratio at 1:0.5. For every Tk 1 of your own capital, your broker may lend you Tk 0.5. That is a 50% margin loan against own funds.
Put Tk 100,000 of your money into a margin account and your broker can extend Tk 50,000 of credit. Your total buying power becomes Tk 150,000. You now own Tk 150,000 worth of shares while having put down only Tk 100,000 of your own. The other Tk 50,000 is debt owed to the broker, secured against the shares themselves.
The math cuts both ways. If those shares rise 10%, your Tk 150,000 position becomes Tk 165,000 — a Tk 15,000 gain on your Tk 100,000 stake, or 15%. If they fall 10%, you lose Tk 15,000 on the same Tk 100,000 — also 15%, in the opposite direction. Leverage does not change the move. It changes the consequence of the move.
When the Broker Calls
The ratio is only half the story. The other half is what happens when prices move against you.
When the value of your margin-purchased securities falls below a regulatory threshold, your broker issues a margin call: deposit additional funds or additional securities to restore the equity cushion. You have a short window to act. If you do not, the broker is required — not permitted, required — to sell your securities to recover the loan.
That sale is not your decision. It is not your timing. It is forced liquidation, and it happens at whatever bid is available in the market at the moment the broker hits the sell button.
The Cascade
Here is where one investor’s problem stops being one investor’s problem.
When the market falls sharply, margin calls are not issued one at a time. They are issued in waves, simultaneously, across every brokerage in Dhaka. Every leveraged position whose equity cushion has been eroded receives a demand for cash or collateral. The investors who cannot meet the demand have their shares sold by the broker.
Those forced sales hit the order book as market orders. They push prices lower. Lower prices erode the equity cushion of the next layer of leveraged positions. Those positions trigger margin calls. Those calls go unmet. More shares get force-sold. Prices fall further. The cycle is self-reinforcing.
This is what happened on March 3-4, 2026. The trigger was geopolitical — Middle East tensions and LNG import worries. The amplifier was leverage. The DS30 lost 91 points under heavy pressure. Banking, pharma, textile, and telecom all sold off together, because forced selling does not discriminate by sector. It sells whatever the leveraged investor was holding.
May 2026 was the same mechanic on a slower fuse. Fitch’s negative outlook started the slide. The Tk 9,800 crore erosion across four sessions was the cascade working through positions one margin call at a time.
Who Can Actually Borrow
Under the 2025 rules, not everyone qualifies. The minimum investment is Tk 500,000 averaged over a year. The minimum experience is one year of secondary-market trading. Regular income is required, which explicitly excludes students, homemakers, and retired persons without ongoing earnings.
Eligible securities are restricted to A-category stocks with P/E up to 40. B-category, Z-category, G-category, SME board, ATB, and OTC are all ineligible — which means the 15 of 36 banks that landed in Z-category cannot be bought on margin at all. Margin funds also cannot be used for IPO subscriptions, block trades, or director purchases of their own company’s shares.
The High Court has sought BSEC’s explanation on the legality of these revised rules after an investor writ petition in November 2025. That case is still open.
What This Means Before You Borrow
The 1:0.5 ratio is the gentlest leverage Bangladesh has seen in years. BSEC raised it to 1:1 in May 2022 to prevent a crash. The current limit is a deliberate brake.
But a brake on the ratio is not a brake on the cascade. As long as any leverage exists in the system, forced selling will amplify declines whenever the index turns. The March and May 2026 selloffs are the proof. If you are considering a margin facility from your broker, the question is not whether you can afford a 50% loan against your capital. The question is whether you can afford to be the position the broker sells when DSEX drops 75 points before lunch.