Shares in Quebec-based Valeant Pharmaceuticals, once one of Canada's most valuable companies, plummeted 13 per cent on Tuesday.

The fall represented a new low for the drugmaker, which makes various pharmaceutical drugs and owns the contact lens maker Bausch & Lomb. In recent months the company has been mired in scandal, the subject of drug-pricing investigations and improper accounting allegations.

Here is a timeline of the company's rise and fall.

March 14, 2017

Ackman Pershing Square

William Ackman, founder and CEO of hedge fund Pershing Square Capital Management, has sold his stake in Valeant Pharmaceuticals. (Reuters)

Shares fall 13 per cent in pre-market trading, down $1.55 at $10.56 US. The drop follows an announcement that William Ackman's Pershing Square Capital Managment has sold its final stake. Ackman will suffer a $3-billion loss.

"We elected to sell our investment and realize a large tax loss which will enable us to dedicate more time to our other portfolio companies and new investment opportunities," he said in a statement.

Jan. 10, 2017

The company sells its skin care brands CeraVe, AcneFree and Ambi to L'Oreal to raise more than $2 billion. It also sold its interest in Dendreon Pharmaceuticals to Chinese company Sanpower for $819.9 million.

Nov. 17, 2016

Former Valeant executive Gary Tanner is arrested and charged with running a fraud-and-kickback scheme. Andrew Davenport, formerly the chief executive of Philidor, a mail-order pharmacy, was also charged. The two are accused of conspiring to set up Philidor as a market to distribute Valeant drugs.

Nov. 8, 2016

Shares tumble to a six-year low as the company cuts its 2016 forecast. Shares lose more than 18 per cent of their value in Toronto to close at $20.85. In New York, the stock lost almost 22 per cent, closing at $14.98 US. "We continue to need to address legacy issues, including negative press coverage, litigation and talent retention and severance," CEO and chairman Joseph Papa tells investors on a conference call.

Oct. 31, 2016

The news agency Bloomberg reports that U.S. prosecutors are investigating a possible fraud case involving Valeant's former CEO J. Michael Pearson, and Howard Schiller, the ex-chief financial officer.

Aug. 9, 2016

U.S. probes Valeant Pharmaceuticals5:57

Shares soar more than 20 per cent as the company announces a reorganization. Two days later, the Wall Street Journal reports that U.S. prosecutors have opened a criminal investigation into the company to probe whether it hid its relationship with a specialty pharmacy from insurers.

June 14, 2016

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Joe Papa was named Valeant Pharmaceuticals chief executive officer in April 2016. (Ryan Remiorz/Canadian Press)

Joseph Papa, who was appointed Valeant's new chairman and CEO in April, says he hopes to restore the company's stature. "I believe that the point of view of being one of the largest companies in Canada is an admirable goal I would absolutely like to do," he tells the media after speaking to Valeant shareholders at their annual meeting.

May 16, 2016

Valeant says it will offer rebates of up to 40 per cent on Nitropress and Isuprel, two heart drugs. The price of Nitropress increased 310 per cent and Isuprel 720 per cent since Valeant acquired them from Marathon Pharmaceuticals in 2015.

April 27, 2016

U.S. lawmakers accuse Valeant of gouging patients during a congressional committee. Senators say an investigation found the 30-year-old drug Syprine, which was acquired by Valeant in 2010, has seen a price increase of more than 3,000 per cent.

March 28, 2016

Shares fall 6.4 per to $29.09 as CEO J. Michael Pearson is subpoenaed by a congressional committee, investigating the soaring prices for prescription medicines.

March 21, 2016

CEO Michael Pearson steps down as investor Bill Ackman joins the board. Pearson had earlier in March told investors they couldn't file quarterly earnings, owing to an accounting error. Investors respond to the organizational shakeup as shares rise 12 per cent on the TSX to $39.28.

Nov. 2, 2015

Short-seller Citron Research releases a report, calling the company's stock "toxic." It also suggests the company will have difficulty paying its debt.

Oct. 30, 2015

Valeant cuts ties with mail-order pharmacy company Philidor, after a report from Citron Research accused the company of "fraud." The report says Valeant hadn't fully disclosed its relationship with the mail-order pharmacy company Philidor. Earlier in the month, Valeant says they've been subpoenaed by U.S. prosecutors investigating its drug pricing and distribution policies. Billionaire investor Bill Ackman, however, pledges his support to the company, buying two million shares in Valeant.

Sept. 2, 2015

Valeant Pharmaceuticals buys eye surgery product maker Synergetics USA for $192 million.

July 24, 2015

Valeant passes RBC to become most valuable company on TSX.

March 9, 2015

Billionaire investor William Ackman reveals his Pershing Square Capital Management hedge fund has purchased a five per cent stake in Valeant.

May 27, 2013

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In July 2015, Valeant became the most valuable company on the TSX. (The Canadian Press)

In a mammoth deal, Valeant buys eye-care company Bausch & Lomb for $8.7 billion. Valeant shares climb more than 10 per cent to an all-time high of $95.82 in afternoon trading on the TSX.

June 21, 2010

Mississauga-based Biovail Corp. merges with California-based Valeant