Diversified miners BHP Billiton and Rio Tinto were unsurprisingly the top two companies in the list determined by market capitalisation, followed by leading Australian gold producer Newcrest Mining and underdog favourite Fortescue Metals Group.

Rio’s listed subsidiary Coal & Allied was ranked fifth with a market cap of $9.05 billion as of October 1, a 33% gain year-on-year.

Queensland coal producer and Brisbane port operator New Hope was ranked eighth with a market cap of $4.17 billion, followed by Macarthur Coal in ninth position with a market cap of $3.46 billion.

The leading pulverised coal injection coal exporter survived multiple takeover attempts this year, with its market cap soaring 49% year-on-year as a result.

Whitehaven Coal is yet to be taken over, and was ranked 11th with its market cap increasing 69% from last year to $3.09 billion.

Aquila Resources, a Queensland coal producer and significant Western Australian and South African iron ore and manganese explorer, took 13th position with its market cap gaining 47% year-on-year to $2.68 billion.

Mozambique pioneer Riversdale Mining leapt up 10 places this year to 17th spot, with its market cap increasing 141% year-on-year to $2.51 billion.

Yesterday the Benga mine operator confirmed it had received an indicative $15 per share approach from Rio, but there was no guarantee a formal offer would be launched.

Coming in at 18th place with $2.43 billion was Centennial Coal, which has been acquired by Thai energy giant Banpu since the October 1 cut-off point for the list.

Gloucester Coal’s market cap surged 218% year-on-year to $1.65 billion as the company undertook significant equity raisings, which diluted commodity trader Noble Group’s stake from 87.7% to 65.35%.

Aston entered the list in 26th place after debuting on the Australian Securities Exchange a few months ago.

Its market cap was $1.19 billion as of October 1, but has since surpassed the $1.5 billion mark.

Coal of Africa slipped from 29th last year to 44th position as green tape issues struck its Vele colliery in South Africa in August.

Wollongong coal producer Gujarat NRE Coking Coal was in 56th position with a market cap of $516 million while Cockatoo Coal was 67th with $412.54 million.

Promising Canadian thermal coal hopeful Coalspur was the last coal company in the ASX top 100 in 74th place with a market cap of $362 million.

Given the healthy appetite for coal stocks, most of these companies had very low debt to market cap ratios.

While Gujarat’s was 26%, Aston’s ratio was 47% due to its considerable investments in infrastructure and equipment.

Ernst & Young noted that the 13 coal companies in its list had seen their cash levels increase by 2% this year compared to 26% for the whole index.

The accounting firm also observed that their average debt levels increased by 11% compared to a 41% decrease for the whole index.

E&Y said coal companies had increased their capital investment this year while coal price rises did not start having an impact until May.

Coal stocks were also hurt by the uncertainty surrounding the super mining tax proposals coming from the federal government.