The Stockholm Stock Exchange is trading slightly lower at midday, following declines in international markets. Sentiment is weighed down by increased anxiety regarding the Iran conflict after new threats from Donald Trump suggesting that time is running out. Both oil prices and global yields are rising during the session.

In corporate news, Sveafastigheter is merging with Klarabo to create the largest listed residential real estate company on the exchange.

At around 12:45 PM, the OMXS30 index was down 0.18 percent at 3,031.10. Shares worth approximately SEK 6.3 billion had changed hands on the Stockholm bourse.

Energy was the best-performing major industrial sector, posting a gain of 1.18 percent. At the other end of the spectrum, consumer discretionary lagged the market, falling 1.17 percent.

Among the blue-chip stocks in the OMXS30 index, Hexagon B rose 2.9 percent while Ericsson B gained 1.7 percent. The weakest performers were Addtech B, down 2.8 percent, and EQT, which shed 2.3 percent.

Sveafastigheter and Klarabo are joining forces through a merger where Sveafastigheter will be the surviving entity. Simultaneously, Klarabo is acquiring a residential portfolio from SBB comprising approximately 4,100 apartments. The combined company is expected to become Nasdaq Stockholm's largest listed residential property firm, with around 26,500 apartments and a property value of approximately SEK 47 billion.

Klarabo shareholders are being offered nine new shares in Sveafastigheter for every 22 shares held in Klarabo. The merger consideration implies a valuation of Klarabo of approximately SEK 2 billion, representing a 0.6 percent premium over the last closing price. Klarabo is also proposing an extraordinary dividend of SEK 1.40 per share.

Klarabo's shares were unchanged following an initial dip, while Sveafastigheter rose 0.6 percent. SBB B climbed 10.6 percent.

Steelmaker SSAB has decided to invest SEK 3.3 billion in a new quenching line in Oxelösund. The investment will increase capacity for SSAB Special Steels' most profitable products and offers an attractive financial return. The stock rose 1.3 percent.

Maha Capital and Blue Water Acquisition Corp. IV have jointly decided to terminate the previously announced process regarding a potential reverse SPAC transaction, thereby cancelling the non-binding letter of intent in its entirety. Maha's shares rose 0.2 percent.

Residential platform Hemnet fell 6.2 percent. The company reported net sales of SEK 116.6 million for April, a 21 percent decrease compared to the same month last year. Meanwhile, the average revenue per listing (ARPL) increased by 11 percent.

Pharmaceutical companies AstraZeneca and Daiichi Sankyo have received FDA approval in the US for Enhertu for two new indications in HER2-positive early breast cancer. The approvals cover both neoadjuvant treatment before surgery and adjuvant treatment after surgery, based on the Phase III DESTINY-Breast11 and DESTINY-Breast05 trials, respectively. AstraZeneca shares rose 0.6 percent.

Investment firm Bure reported a decrease in net asset value during the first quarter compared to the end of the year. Since the end of the reporting period, the net asset value has increased significantly, supported in part by the share price surge in its holding Silex. The stock fell around 2.4 percent.

Tech company Smart Eye swung to an EBITDA profit of SEK 26.9 million in the first quarter, from a loss of SEK 17.9 million in the same quarter last year. Revenue also increased. The stock surged 7.6 percent.

On Sunday evening, a rockfall occurred at Boliden's mine in Kristineberg, Lycksele municipality. A man who was trapped during the incident has now been rescued, according to SVT. Boliden shares fell 0.8 percent.

In analyst news, Dagens Industri has issued a 'buy' recommendation for SKF, which faces a corporate split this autumn. The newspaper sees an upside of at least 30 percent. The stock rose 0.2 percent.

Dagens Industri has issued a 'sell' rating on Alleima. The stock fell 6.6 percent.

Citigroup has upgraded Saab to 'neutral' (from 'sell') with a price target of SEK 527. The stock rose 1.4 percent.

Ålandsbanken has initiated a positive outlook on Beijer Ref. The stock fell 0.5 percent.