A CEASEFIRE may have been declared between BHP Billiton's Queensland projects and a trio of unions, but past industrial action may have had an impact on the nation's superannuation stocks.
In the six months since the Electrical Trades Union, Construction Forestry Mining and Energy Union and Australian Manufacturing Workers Union pumped up its industrial action, BHP's share price fell by almost 18%.
Rolling strikes, stop-work meetings and cancelled action at a moment's notice were a thorn in the side of the resources powerhouse.
Falling coal prices, European debt concerns and global economic jitters were also likely contributing factors, but with its stocks the darling of many superannuation funds, any hit to share prices is a hit to retirement nest eggs.
The concerns were enough for the Australian Council of Trade Unions to issue a letter to members warning them of the "shareholder risk" for those with super funds relying on the resources industry.
The ACTU stated it was difficult to pinpoint how much the action would cost the company, but if it hurt coal exports and BHP was forced to lower its expectations, it "could be extremely harmful to the overall value of the stock and its value as an investment for industry superannuation funds".
The ACTU then called on its members to ask fund managers about the dispute and encourage funds to push for BHP to settle with the unions.
Earlier this week, APN reported the dispute did more damage to BHP's Central Queensland coal exports than the 2011 floods that ravaged the region and inundated BHP operations.
Each side has been in mediation since earlier this month, with both unions and BHP abiding by a strict media blackout.
BT Investment Management analyst Tim Barker said there was "no doubt" that union action affected share values.
However, with BHP's laundry list of industrial activities, any number of other elements would contribute.
Mr Barker said the action would likely have had a "marginal impact" on prices.
"You look at it and compare perhaps the performance between it and similar stocks, which indicate (the industrial action) was having an impact," he said.
"But BHP is so diverse that US gas prices or oil prices could have an impact."
He said as Australia's largest stock, "a large percentage" of Australians would have had exposure to its fall.
"The resource market has fallen 30% in the past 12 months.
"Most people have had exposure to the resource market in some form."
Update your news preferences and get the latest news delivered to your inbox.