In afternoon trade, the S&P/ASX 200 Index (ASX: XJO) is on course to record a decline. At the time of writing, the benchmark index is down 0.4% to 8,382.7 points.

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

ASX Ltd (ASX: ASX)

The ASX share price is down 3.5% to $66.77. Investors have been selling the stock exchange operator's shares after it released an update on its troubled CHESS replacement project. It will now do it in two releases, with CHESS Release 2 implementation targeted for 2029 with estimated project costs of between $270 million and $320 million. CEO Helen Lofthouse said: "We continue to prioritise the safe delivery and reliability of the CHESS project. This is reflected in our proposal to implement the project over two releases and to implement Release 2 in 2029, which is expected to allow time for industry preparation and readiness activities following extensive stakeholder engagement."

Commonwealth Bank of Australia (ASX: CBA)

The Commonwealth Bank of Australia share price is down 3% to $155.45. This is despite there being no news out of Australia's largest bank. However, with the big four banks all up strongly over the past 12 months, some investors could have decided to take some profit off the table today. Even after today's pullback, CBA's shares are up over 50% since this time last year. This was despite almost all major brokers describing (and continuing to describe) its shares as being extremely overvalued. For example, Citi has a sell rating and $91.50 price target, implying over 40% downside.

Iperionx Ltd (ASX: IPX)

The Iperionx share price is down 2.5% to $4.39. This morning, this titanium alloys producer announced the successful acquisition of Blacksand Technology's assets and intellectual property portfolio. Management notes that the acquisition secures IperionX's exclusive commercial rights to the patents and proprietary technologies. Its CEO Taso Arima said: "The acquisition of the award-winning intellectual property portfolio is an important milestone for IperionX – delivering direct control of the technologies and innovations that underpin our plans to re-shore an end-to-end, lower-cost U.S. titanium supply chain that is critical to America's economic and national security."

Sayona Mining Ltd (ASX: SYA)

The Sayona Mining share price is down 8.5% to 3.2 cents. This is despite there being no news out of the lithium miner. Though, it is worth noting that Sayona Mining raised capital at 3.2 cents per new share last week. Firm commitments were received from institutional and sophisticated investors to raise $40 million via an underwritten unconditional placement. The company made the move ahead of its proposed merger with Piedmont Lithium (ASX: PLL). It notes that "the Equity Raising will ensure the combined entity has significant balance sheet strength and flexibility and will enable the merged business to progress value-accretive growth opportunities across its diverse project suite."