Embattled Canadian marijuana producer Aphria Inc. saw its U.S.-listed shares rebound Thursday, after the company issued a rebuttal to a series of accusations leveled by a short seller even as new allegations were posted.

The short seller, Hindenburg Research, issued another report Thursday, three days after its first batch of research that said Aphria was a “shell game with a cannabis business on the side”and called into question the value of a number of its acquisitions. Aphria issued a lengthy statement Tuesday that defended the operations included in the Hindenburg report and Thursday morning said it has appointed a special committee to review one of the acquisitions.

By the start of trading Thursday, Aphria APHA, +22.84%APHA, +51.00%  stock had lost roughly half its value — U.S. exchanges were closed Wednesday, but the Toronto Stock Exchange, or TSX, where Aphria is also listed, remained open — but shares on the New York Stock Exchange closed up 23% Thursday.

Hindenburg’s report prompted GMP Securities analyst Martin Landry to place Aphria’s rating and price target under review. “We believe that management’s credibility may have been impacted by the allegations raised in this report,” Landry wrote in a note to clients Tuesday. “It is unclear at this point how the company will re-establish trust with investors. Hence, until we have more visibility on the action plan of Aphria’s board of directors, we will put our rating and target under review.” Previously, Landry had a $22 price target and rated the stock a buy.

Hindenburg’s Thursday update focused on the Aphria-backed Liberty Health Science, which trades on the Canadian Securities Exchange under the ticker LHS. Hindenburg said that its research into Liberty uncovered “multiple irregularities that raise more questions around believed undisclosed insider self-dealing.” Liberty shares closed up 15% to C94 cents Thursday.

Aphria suffered from another issue this week: a Health Canada inspection in June 2018 revealed that one of the company’s facilities was not compliant with guidelines around record-keeping, good production practices, and sanitation and maintenance of the facility, according to the agency. Health Canada issued a warning letter — but did not suspend Aphria’s license — and the company took action to bring it into compliance.

Many of the sector’s largest companies slid in Thursday trading. Tilray Inc. TLRY, -1.26%  fell 1.3%, GW Pharmaceuticals PLCGWPH, -3.41%  dropped 3.4%, Canopy Growth Corp. CGC, -3.53%WEED, +7.57%  fell 3.5% and Aurora Cannabis Inc. ACB, -2.22%ACB, +13.53%  dropped 2.2%. Aurora announced Thursday that it had inked a deal with the Luxembourg Health Ministry to supply medical marijuana to the country; Luxembourg has received an initial 20-kilogram shipment, the company said.

Cronos Group Inc. CRON, -2.70%  , CRON, +7.95%  , which said earlier this week it was in talks with Marlboro maker Altria Group Inc. MO, +0.00%  for an investment, slid 2.7%.

Also Thursday, Canopy said it had acquired vaporizer maker Storz & Bickel GmbH & Co. KG for €145 million ($165 million) in cash. The German company has 17 filed patents and the founders of Storz are expected to remain part of the business. Canopy has at least a $4 billion war chest from the investment Constellation Brands Inc. STZ, -0.24%  made earlier this year. Acquisitions are one of the things Canopy Chief Executive Bruce Linton told MarketWatch in October that he plans to accomplish with that cash.

The ETFMG Alternative Harvest ETF MJ, -1.96%  has lost 15% this year, as the S&P 500 index SPX, -0.15%  gained 0.7%. Aphria shares have dropped 62% this year.