It's been a great day for the S&P/ASX 200 Index (ASX: XJO) so far this Wednesday. After a rough and wild session yesterday, the ASX 200 seems to be in full recovery mode, which is good news for investors. But not so much for anyone who owns Sigma Healthcare Ltd (ASX: SIG) shares. At least at first glance.

That's because Sigma Healthcare shares are not active on the ASX today. The healthcare stock closed at $3.03 a share yesterday after enjoying a 12.22% boost following the company's latest earnings report.

As we covered at the time, this was a very impressive update. Sigma informed investors that the unlisted Chemist Warehouse chain delivered a 13% rise in total sales to a record high of $5.15 billion over the first half of the 2025 financial year. Sigma is, of course, barrelling towards a full merger with Chemist Warehouse.

Even more luminous were Chemist Warehouse's profits. Sigma revealed that the pharmacy chain boosted its net profits before tax by a whopping 36.1% to $436.8 million.

It therefore wasn't too shocking to see investors push up the Sigma share price so enthusiastically yesterday.

But today, those shares are frozen at $3.03 each, with trading halted.

Sigma shares halted for crucial Chemist Warehouse merger vote

Yep, this morning, Sigma put out an ASX release just before market open. This release informed investors that Sigma had requested an "immediate implementation of a trading halt". Fortunately, the company provided a detailed explanation as to why this halt was being requested:

The trading halt is requested pending announcements relating to the outcome of the Sigma shareholder meeting and the Chemist Warehouse scheme meeting which will both be held today.

As you know, these meetings relate to the merger between Sigma and Chemist Warehouse, and the passing of certain resolutions at both meetings are conditions precedent to the implementation of the merger.

Sigma requests the trading halt to allow Sigma to manage its continuous disclosure obligations and to ensure that Sigma shares are not trading on an uninformed basis.

Investors have known that this shareholder meeting was to occur today for a while. Sigma's board has already unanimously recommended that shareholders give the deal the green light. That's after the final regulatory approvals were granted late last year. If shareholders vote to proceed with the Chemist Warehouse merger, it will be implemented on 12 February next month.

Given the euphoric response from investors since the merger was first proposed in late 2023, it would be surprising to see it fail this vote. Since December 2023, the Sigma share price has ballooned by roughly 300%, rising from under $1 a share to the $3.03 the company is frozen at today.

Sigma expects its shares to resume trading by tomorrow's session at the latest. At the current share price, the company has a market capitalisation of $4.94 billion.