The S&P/ASX 200 Index (ASX: XJO) is on form on Monday and charging higher. At the time of writing, the benchmark index is up 0.65% to 7,839.6 points.

Four ASX shares that have failed to follow the market higher today are listed below. Here's why they are falling:

Austin Engineering Ltd (ASX: ANG)

The Austin Engineering share price is down 2% to 41.7 cents. Investors have been selling this engineering company's shares after they traded ex-dividend this morning. Last month, the company released its half year results and revealed a fully franked 0.6 cents per share interim dividend. This will be paid to eligible shareholders next month on 9 April. Based on its last close price, this equates to a 1.4% dividend yield for investors.

DroneShield Ltd (ASX: DRO)

The DroneShield share price is down over 6% to $1.02. This appears to have been driven by profit taking from investors after some strong gains in recent weeks. In fact, the counter drone technology company's shares are still up by 65% since this time last month despite today's pullback. Investors appear to have been betting on increased defence spending giving the growing company's sales a major boost in 2025.

Meridian Energy Ltd (ASX: MEZ)

The Meridian Energy share price is down 1.5% to $4.90. This follows the release of the New Zealand based energy company's monthly update. According to the release, national electricity demand in February 2025 was 5.2% lower than the same month last year. This led to Meridian Energy reporting a 1.9% decline in retail sales volumes compared to the same period in February 2024.

Ramelius Resources Ltd (ASX: RMS)

The Ramelius Resources share price is down almost 1.5% to $2.17. Investors have responded relatively negatively to news that the gold miner is merging with Spartan Resources Ltd (ASX: SPR). The two parties have agreed on a deal that will see Ramelius acquire all outstanding Spartan shares for $0.25 in cash and 0.6957 new Ramelius shares per share. Ramelius' managing director, Mark Zeptner, said: "Ramelius is delighted to be combining with Spartan, which will see Ramelius' Mt Magnet Production Hub supercharged by the integration of Spartan's high-grade Dalgaranga Mineral Resource. The combination will see Mt Magnet deliver higher ounces, at higher grade, with higher margins. With the Spartan Effect, Ramelius has a vision for the Combined Group to be a +500koz/pa producer in FY30."