The group filed for protection from its creditors late last month, giving it four months to find a solution to its astronomical debt or go bankrupt and become Spain's biggest-ever corporate failure.
Since then, creditors, unions and the government have been trying to get a clearer idea of the group's financial situation, and a grouping of seven banks has appointed auditors KPMG to comb through the accounts of the company and its 600-plus subsidiaries, according to the Bloomberg financial news agency.
"They are very indebted... their total liabilities could be more than 25 billion (euros)," Industry Minister Jose Manuel Soria estimated Friday.
As the December 20th general elections approach, Prime Minister Mariano Rajoy has yet to comment on the possibility of a Spanish company that employs 28,700 people globally -- including nearly 7,000 in his own country - going down.
The government has ruled out any form of state bailout, with Economy Minister Luis de Guindos stressing the need "to find out exactly what the accounting and debt situation of the company is".
Investors already burnt
The world player in solar and wind power, biofuels and water management says it had a gross debt of nearly nine billion euros at the end of September.
But lawyers who filed a legal complaint against the board on Monday say it could stand at 25 billion euros.
"Investors have been burnt by other bankruptcies in Spain, when debt was found hidden away," said ISM Capital analyst Antoine Bourgault.
He pointed for instance to the surprise, high-profile bankruptcy of Spanish packaged seafood giant Pescanova in 2013, which had secretly amassed a pile of debt.
Unions too are waiting, worried about mass layoffs.
Francisco Carbonero, head of the CCOO union in the southern region of Andalucia where Abengoa is headquartered -- said he was holding out for the KPMG report.
"For the moment, they haven't come out with a redundancy plan," he said, adding nevertheless that a large number of short-term contracts had not been renewed over the past few weeks.
The group, which is present in some 20 countries, makes nearly 87 percent of its turnover abroad - with North America its largest market, followed closely by South America.
Already in Brazil, unions are concerned, with the Sintepav grouping that represents workers in the country's construction sector saying it is expecting 5,000 jobs to be cut.
Spain's banking sector, which is only just emerging from the devastating crisis that saw it rescued with a 41-billion-euro eurozone bailout, could also be be hurt.
"Banks' bottom-line profits this year will likely fall short of our forecasts, as they start provisioning for the potential losses they could face," said the Standard & Poors ratings agency.
"Given the company's large scale... and its high leverage... Abengoa is a significant exposure for most of the Spanish banks we rate," it said.
But it added that the pressure was not exclusively on Spanish banks, as the group also had access to foreign lenders given its large worldwide footprint.
Small-scale shareholders fear they will get burnt again.
"After having overcome the financial crisis, with the hard costs that implied for individual savers, and having witnessed fraud directly linked to bad business practices, it seemed that the wind was changing," said Javier Cremades, head of Aemec, an association representing minority shareholders.
"But unfortunately that has not been the case," he wrote in the El Pais daily.
By Laure Fillon