Westgold Resources (ASX:WGX) and Yancoal (ASX:YAL) are set to be included in the ASX 200 and 300 indexes, as three formerly high-profile stocks were dropped.

Those dropped were Domain, the property listing group 48% owned by Nine Entertainment, along with Nanosonics and Strike Energy.

The best-known new member of the indexes is the Mexican wannabe fast food chain, Guzman y Gomez, which has yet to prove itself.

An interesting stock dropped from the ASX 200 was Domino's Pizza, the once very high-profile fast food group that has fallen on hard times with weak growth in major markets like Australia and Japan. That is a big fall from grace for Domino's.

Sandfire Resources, the Australian miner with its centrepiece operations in Spain, made it into the ASX 100, along with Hub24, a Melbourne-controlled financial services group.

Arcadium Lithium was dropped from the ASX 100 but remains in the ASX 200 after it put its WA spodumene mine at Mount Cattlin in WA on care and maintenance last week.

The news saw mixed market fortunes for Westgold and Yancoal on the ASX on Monday, even though the change doesn't happen until later this month.

Yancoal shares jumped 4.5%, but Westgold shares fell nearly 3.5% after it revealed a new mine development in WA. Investors just hate companies spending money on new investments, and that view underlines how little knowledge many investors have of how companies operate and the essential part new investment plays in growth.

"Westgold's admission to the prestigious S&P/ASX 200 index is a direct result of the efforts of our people delivering safe and profitable ounces for our shareholders," Westgold CEO Wayne Bramwell said on Monday.

"This strategy has seen Westgold's market capitalisation grow to approximately $2.7 billion at market close on September 6."

Westgold is wrapping up its $1.2 billion acquisition of Karora Resources, a Canadian-Australian gold group, in July, which cemented its place as a top-five Australian gold producer.

Meanwhile, Yancoal CEO David Moult said in a statement, "We were encouraged to see the notable increase in the company's market valuation, average daily turnover, and shareholder base during recent years as we recovered from extended rain disruptions and our free float increased."

"Yancoal provides investors with direct exposure to international coal markets. In the 12 months to June 30, 2024, Yancoal operations produced over 62 million tonnes of ROM (run-of-mine) coal and 36 million tonnes of attributable saleable coal. Our anticipated production rate over the remainder of 2024 puts us on track to be the second-largest coal producer in Australia."

"We see the company's inclusion in the S&P/ASX indices providing a further opportunity to expand our investor base and bolster the trading liquidity of our shares."

Yancoal is tipped to be a frontrunner if and when the five Anglo American coal mines in central Queensland reach the sale stage.