Up 132% in a year, are Sigma Healthcare shares still a good buy post the Chemist Warehouse merger?

Sigma Healthcare Ltd (ASX: SIG) shares closed in the green on Monday.

Shares in the S&P/ASX 200 Index (ASX: XJO) healthcare stock finished the day up 0.33%, changing hands for $3.02 apiece.

That sees the share price up an eye-popping 132.31% since this time last year.

Or enough to turn a $10,000 investment into $23,231. Plus the 1 cent per share in partly franked dividends you'd have gotten over the 12 months.

A lot of those gains were delivered during the lengthy leadup with its merger with privately held Chemist Warehouse.

With that merger now done and dusted, is the ASX 200 healthcare stock still a good buy today?

Are Sigma Healthcare shares a buy?

Ord Minnett's Tony Paterno recently ran his slide rule back over Sigma Healthcare shares (courtesy of the Bull).

"Sigma and Chemist Warehouse merged in February 2025," Paterno said. "Prior to the merge, Chemist Warehouse's first half 2025 trading update highlighted continuing robust operating momentum, with like-for-like sales up 10.3%."

Paterno added:

Chemist Warehouse opened 19 new stores. The company posted strong earnings before interest and tax margins underpinned by robust sales growth, new supply agreements and efficiencies in operating expenditure.

But with Sigma Healthcare stock having more than doubled over the past year, Paterno doesn't recommend adding more shares to your portfolio today.

Though he's not recommending selling either.

"We retain a positive stance on the quality of the Chemist Warehouse business, but downgrade Sigma to a hold on valuation grounds," Paterno concluded.

What's the latest from the ASX 200 healthcare stock?

Sigma Healthcare shares are up 9.42% since the merger with Chemist Warehouse was finally completed on 12 February.

The last price-sensitive news from the company was a trading update, which was released on May 6.

The pharmacy giant reported that for the nine months to 31 March, normalised earnings before interest and tax (EBIT) growth for the newly merged group was broadly consistent with the 36% growth achieved by Chemist Warehouse Group for the first half of FY 2025 compared to the first half of FY 2024.

Normalised EBIT excludes merger-related transaction costs. The company said it had incurred transaction costs of $42.4 million as at 31 March.

With investors appearing to have priced in even stronger growth metrics, Sigma Healthcare shares closed down 6.7% on the day of the update.

Shares have yet to recover the $3.15 closing price posted on 5 May.