The changes only apply to initial public offerings and backdoor listings, but research by S&P Global Market Intelligence shows that 212 listed junior miners would not be admitted to the list if subjected to the new thresholds.

New listings must now have net tangible assets of more than $A5 million or a market capitalisation of greater than $20 million, as well as a 20% free float and at least 100 shareholders with a minimum of $5000 of shares each.

Of the 212 S&P found, as of last week, 27 had market caps of $10-20 million, 55 had net tangible assets of $3-5 million, and eight fall between the current and proposed figures in both categories.

A total of 138 companies also failed to meet the current assets test criteria.

“Juniors such as Explaurum and Canyon Resources find themselves in the unique position of falling just short of both the new market capitalisation requirements and the new tangible asset requirements,” S&P said.

“Explaurum reported tangible assets of $4.7 million at the end of the December 2015 quarter and had a market value of $15.4 million, while at the end of May, Canyon Resources reported $4.4 million in tangible assets and a value of $19.4 million.”

Nearly 40% of the list are precious metals-focused companies.

S&P said 592 ASX-listed miners held $2.18 billion in cash at the end of March, with the 212 on the list accounting for just 6% of the total.

The 212 spent only a combined $18.6 million on exploration during the quarter out of a total spend of $161.5 million.

“These shortcomings highlight the challenges already facing the smallest junior miners; the proposed changes will only intensify their struggles by further limiting their options,” S&P said.

OnMarket BookBuilds has launched a petition regarding the changes and accounting firm BDO is among those to have made a submission.

This week, the Australian Securities and Investments Commission released a report on ASX listing standards, finding that the market had met its statutory obligations.

“The fast-paced nature of global and domestic financial markets underscore the importance of ASX taking a forward-looking and proactive approach to ensure its listing standards continue to deliver key benefits to Australians,” ASIC Commissioner Cathie Armour said.