The S&P/ASX 200 Index (ASX: XJO) has given back its morning gains and dropped into the red. At the time of writing, the benchmark index is down slightly to 8,349 points.

Four ASX shares that are falling more than most today are listed below. Here's why they are dropping:

Downer EDI Ltd (ASX: DOW)

The Downer share price is down 6.5% to $5.33. Investors have been selling this integrated services provider's shares after it was hit with legal proceedings by the ACCC. This relates to the company's Spotless business. The competition regulator stated: "The ACCC alleges that on three occasions between April 2019 and August 2022, Ventia and/or Spotless made or attempted to make arrangements or understandings containing provisions which had the purpose, effect or likely effect of fixing, controlling or maintaining the prices at which these services would be supplied to Defence under specific programs of works. The ACCC alleges this is a breach of the cartel provisions in the Competition and Consumer Act."

Peter Warren Automotive Holdings Ltd (ASX: PWR)

The Peter Warren share price is down 13% to $1.46. This morning, the automotive retailer released a disappointing trading update. It advised that growing industry headwinds have resulted in a recent deterioration in trading conditions. As a result, it now expects underlying profit before tax for the first half of FY 2025 to be in the range of $6 million to $8 million. This is down from $34.4 million in the prior corresponding period.

Platinum Asset Management Ltd (ASX: PTM)

The Platinum share price is down 20% to 68.2 cents. This has been driven by the struggling fund manager's shares going ex-dividend this morning for a special dividend. Earlier this week, the company announced a fully franked special dividend of 20 cents per share. This represented a 23.5% dividend yield at yesterday's close price. Platinum is paying this dividend to eligible shareholders at the end of the month on 31 December.

Syrah Resources Ltd (ASX: SYR)

The Syrah Resources share price is down 28% to 19 cents. Investors have been selling this graphite producer's shares after it declared a force majeure at its Balama project in Mozambique. It said: "With conditions continuing to deteriorate across Mozambique and further National Government opposition protest actions recently announced, Syrah is unable to undertake a production campaign at Balama in the December 2024 quarter that is required to replenish finished product inventory, and for customer sales." Unfortunately, Syrah also revealed that protest actions have triggered events of default in its loans with the US government.