An investigation into alleged, huge-scale government kickbacks and a rout in global oil prices have already sent Brazil's oil company reeling into the new year. Now, concerns are mounting that what's ailing Petrobras could reach well beyond the state-run energy giant.
The battered oil company, also known formally as Petroleo Brasileiro Petrobras, took another hit on Tuesday when Moody's placed contractors for its offshore drilling operations under review for downgrade. More than $4.7 billion in debt linked to Petrobras projects sits in limbo as pressures, including a shock to global oil prices and an ongoing corruption investigation, have constrained the state-backed company's ability to float the projects.
Despite a significant boost in production—up 5.3 percent in 2014 over the year prior, to 2 million barrels per day—Petrobras struggles to appease bondholders as it slogs through its own debt crisis. Any further deepening of the state-backed company's woes, though, will likely be linked to the wider fate of Brazil, experts told CNBC.
"This is seen as having a sovereign backstop. When push comes to shove, you'll assume it'll get bailed out and covered by the sovereign," said Win Thin, global head of emerging markets at Brown Brothers Harriman.
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Petrobras, which is currently locked out of international credit markets, is "weighing on the sovereign," Nicholas Spiro, managing director of Spiro Sovereign Strategy, told CNBC in an email. The "sovereign," or Brazilian state, backs Petrobras, which has put further pressure on the country's economy, he said.
While the move by Moody's on Tuesday, as well as its December decision to put Petrobras itself on review for downgrade from a Baa2 rating, are acting as a "blinking yellow light" for investors, outright catastrophe is not imminent, BBH's Thin said.
The "quasi-sovereign" Petrobras, which is theoretically protected by the Brazilian government, will likely stay afloat barring any further hit to Brazil's ratings, Thin said. The time to worry comes if Brazil, currently at a Baa2 rating with negative outlook, falls into junk territory. But Moody's move certainly does not bode well for Petrobras.
Petrobras did not immediately respond to CNBC's request to comment on its credit situation and the corruption investigation.
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Moody's review for downgrade of drilling-linked debt affects billions in notes tied to drillers QGOG and Odebrecht, among others. "The convergence of a number of credit pressures," including a struggling oil industry and liquidity risks for Petrobras, prompted the increased scrutiny, Moody's wrote.
"The decline of oil prices could also materially pressure asset values, a key element in the collateral package of these project bonds," Moody's wrote.
Plummeting Brent crude prices, which hovered around $46 a barrel on Wednesday, have gutted outlooks for oil companies around the world. Petrobras stock sits just above $6 per share, and has lost nearly 50 percent in the last year, and its New York-listed shares were down almost 5 percent on Wednesday.
Petrobras' fundamentals will come under even more scrutiny as the company, among the world's 10 largest in the energy sector, sits mired in at least $170 billion of debt, as CNBC reported last year.
The investigation alleging bribery and corruption by Petrobras employees comes as Brazil and recently re-elected President Dilma Rousseff attempt to implement reforms and stave off sovereign debt issues amid lagging growth.
"Brazil's new government needs the Petrobras scandal like it needs a hole in the head. This couldn't be happening at a worse time from a political and economic standpoint," Spiro told CNBC in an email.
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The breadth of corruption being alleged in the Petrobras case hints that its issues may be "systemic" to Brazil as a whole, Spiro said. But economic trends aren't entirely grim for the Brazilian economy.
Brazil relies less heavily on oil exports than many Latin American or Middle Eastern economies, Thin said. Iron ore, its chief product, accounted for about 13 percent of exports in 2013, while oil sat at about 5 percent.
—Reuters contributed to this report.