Crunch time for under-fire Noble Group?

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Having endured months of slings and arrows from negative research reports and attacks by activists, Noble Group's quarterly earnings later Monday will be squarely in its critics' sights.

In response to a further sharp leg down in its share price late last month and its inability to continue its aggressive share buybacks during the pre-earnings "quiet period," Noble moved forward by three days the release of its earnings report and PricewaterhouseCoopers' (PwC) independent analysis of its mark-to-market valuation methods.

The stock dropped around 20 percent in July alone, and altogether has plummeted around 50 percent since February, when then-anonymous Iceberg Research published the first of a series of negative reports, with the first headlined "Noble Group, a repeat of Enron."

Iceberg's original report alleged that the Singapore-listed commodities trader's accounting treatments were "unusual," result in "fabricated" profit and "intentionally misleads credit agencies and investors."

Noble has consistently and vehemently denied the allegations and has taken multiple steps to improve its transparency to investors, including commissioning the PwC report. The trader also claimed it had identified Iceberg as Arnaud Vagner, a disgruntled ex-employee it fired in 2013; the company filed a lawsuit against Vagner in Hong Kong, alleging "conspiracy to injure." Iceberg has previously refused to confirm or deny whether Vagner is a principal.

Read More Attacks on Noble Group's accounting take their toll

But other analysts and short-sellers jumped on the bandwagon, including a salvo from flamboyant short-seller Muddy Waters, although several analysts said there was nothing in that report that differed substantially from the Iceberg allegations. Muddy Waters alleged Noble used "substance-less accounting" and that the financials of the deal to buy and sell Indonesian firm PT ALH were manipulated; at the time, Noble said "we categorically reject the unfounded allegations."

GMT Research, a private research house, also made critical statements about Noble's accounting; in April, it called the accounting "presumptuous," but added that it is not necessarily fraudulent.

Noble is expected to report net profit of $121.84 million for the April-June quarter, up from the first quarter's $106.62 million, according to a Reuters poll.

However, the actual numbers may not matter much to the stock.

GMT said it is looking more for disclosure changes.

"We want to see the inventory split out from discounted profits… so that it becomes clear what is a hedging profit and what is a future earnings profit," said Robert Medd, an analyst at GMT Research Monday before the release. "From an accounting perspective, we want to try to understand what is the true level of debt at the company and how much of the future value gains are booked on businesses that may never come into operation."

Noble, which is in its quiet period before the earnings release, did not immediately return an emailed request for comment.

Some see positives for the company.

Deutsche Bank, for one, welcomed Noble's move to bring the earnings forward, as well as Noble's affirmation of its liquidity position, seeing it as a positive for the company's bonds, which have suffered amid allegations the company might have struggled to pay a bond redemption last week. Noble redeemed $735 million of its bonds, with $235 million of that an early payment that was due in 2020.

Concerns about Noble's bonds worsened after Standard & Poor's (S&P) in June revised the company's outlook to negative from stable, citing higher earnings volatility and trading risk. But Deutsche Bank believed Noble's latest steps were positive for its credit.

"Bringing forward its results date also means Noble can start defending its share price via on market buybacks sooner. The resources used for the buybacks have so far been manageable for Noble's liquidity position," Colin Tan, a Deutsche Bank analyst, said in a note last week. But he added: "Given the rapid decline in Noble's market capitalization we believe a strategic investor may be needed to restore investors' confidence in the name."

Read More Has Noble fought back the tide of Muddy Waters?

The company has said it's been approached by potential strategic investors.

Others are also chary of the shares.

"Short-term earnings are likely to miss market expectations due to lower trading margins, potential further asset impairments and more conservative revenue recognition after Iceberg's and Muddy Waters' allegations," Wei Bin, an analyst at Maybank Kim Eng, said in a note in late June. He kept a Hold call on the stock, expecting Noble's share buybacks will support the price, but he added that it was too soon to bottom fish the shares.

Some expect the PwC report could boost the shares, however.

"The whole sector is less profitable than it used to be. Noble is suffering from that," GMT's Medd said. "That's not to say that if they get a detailed bill of health from PwC, people (may say) 'that's not as bad as we thought,' and we could see a share price bounce back."

But he also noted that he's pessimistic on whether the PwC report will offer much insight into the company's accounting.

—By CNBC.Com's Leslie Shaffer; Follow her on Twitter