What Is an Open Offer — and Why the New Owner Has to Ask You Too

What it is

Imagine your apartment building has a big investor who quietly buys enough flats to become the single largest owner. Overnight, they control the building — the rules, the direction, everything. You never got a say, and now you're stuck with a landlord you didn't choose. That feels unfair, right?

The stock market has the same problem. When a new party buys a controlling stake in a company, the small shareholders suddenly have a new boss they never voted for. So SEBI's Takeover Code says: if you're going to take control, you must also give ordinary shareholders a chance to sell out and leave. That mandatory offer is called an open offer.

The rule that triggers it

The key number is 25%. The moment an acquirer's stake crosses 25% of a listed company, an open offer is automatically triggered. They can't just keep buying quietly — the law forces them to make a public offer to buy shares from everyone else too.

And it's not a token gesture. The open offer must be for at least 26% of the company — a big enough slice that a meaningful number of small holders can actually exit if they want to. There's also a "creeping" rule: even someone who already owns 25% or more can't grab more than 5% extra in a single year without triggering a fresh open offer.

How it actually works

The acquirer announces a fixed offer price — and this can't be lowballed. The rules force it to be the highest of a few benchmarks, including what the acquirer themselves recently paid and the average market price over the previous 60 trading days. So the offer price is meant to be fair, not a bargain for the buyer.

Then a tendering window opens for a few days. If you own shares, you decide: tender them at the offer price, or keep them. Here's the catch most people miss — an open offer is a right, not an obligation. It's a guaranteed exit door, not free money. If the stock is trading in the open market above the offer price, you're better off just selling on the exchange.

A real example: Adani, Ambuja & ACC (2022)

In 2022, the Adani Group bought the Indian cement giants Ambuja Cements and ACC from Swiss company Holcim — a deal worth over $10 billion. Because Adani was taking control, the Takeover Code kicked in, and Adani had to launch what became the largest open offer in Indian corporate history, worth around ₹31,000 crore. The offer price was ₹385 per share for Ambuja and ₹2,300 for ACC, with a tendering window from 26 August to 9 September 2022.

And here's the twist: it flopped. By the deadline, the market price had run up well above the offer — Ambuja was trading around ₹453 and ACC around ₹2,365, both comfortably higher than what Adani was offering. So shareholders simply didn't tender. Ambuja saw just 1.35% of the offered shares come in; ACC only about 8.28%.

The lesson: an open offer is protection, not a payday. It guarantees you a floor to exit at — but a smart investor checks the live market price first. Sometimes the best response to being asked "can I buy your shares?" is a polite no.