The S&P/ASX 200 Index (ASX: XJO) is on course to end the week on a high. At the time of writing, the benchmark index is up 0.75% to 8,556.6 points.

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

Magellan Financial Group Ltd (ASX: MFG)

The Magellan share price is down a further 8% to $10.49. This is the second day in a row that the fund manager's shares have fallen heavily. On Thursday, Magellan announced a number of executive and investment team changes. This includes the exit of Gerald Stack from his role as Head of Investments after 18 years with the firm. It notes that Stack has been Magellan's Head of Investments for more than a decade and over the past two years has contributed to important initiatives to strengthen the Investment Team. Magellan advised that Stack "now feels the business has the stability and direction it needs for the future and will take some time off before pursuing his next opportunity."

Medadvisor Ltd (ASX: MDR)

The Medadvisor share price is down almost 3% to 18 cents. This appears to have been driven by a broker note out of Bell Potter. Its analysts have downgraded this medtech company's shares to a hold rating (from buy) and slashed the price target on them to 21 cents (from 40 cents). This follows the release of a very disappointing quarterly update which fell well short of expectations.

Origin Energy Ltd (ASX: ORG)

The Origin Energy share price is down 4.5% to $10.70. Investors have been selling this energy company's shares following the release of its second quarter update. Although there were a lot of bright spots in the update, these were overshadowed by a downgrade to Australia Pacific LNG (APLNG) production guidance. Its FY 2025 production guidance for APLNG is now 670–690 petajoules (PJ). This is down 2% to 3% from its previous forecast of 685–710 PJ. This reflects lower-than-expected benefits from well optimisation efforts at Condabri, Talinga, and Orana, as well as reduced performance from non-operated assets and unplanned maintenance.

Pointsbet Holdings Ltd (ASX: PBH)

The Pointsbet share price is down 17% to 81 cents. This has been driven by the release of the sports betting company's quarterly update. Pointsbet posted a quarterly total net win of $69.9 million, which was flat on the prior corresponding period. It also revealed that its normalised EBITDA was negative $3.3 million for the first half.