This year has been a difficult one so far for many companies around the world. As global stock markets plunge, we reveal 30 of the biggest losers as of 31 October, from ailing banks to struggling retailers.

A number of Australian financial institutions have fallen foul of the Labor government's ongoing banking Royal Commission, which has impacted on their share price. Westpac stock, which has also been hit by falling house prices, has sunk from AU$31.25 (US$22.64/£17.37) at the start of January to AU$26.85 (US$19.45/£14.93).

Shares in Hong Kong-listed airline Cathay Pacific have dropped to a nine-year low, down from HK$12.22 (US$1.56/£1.20) at the start of the year to HK$9.96 ($US1.27/£0.98). The reason? A massive data breach that has affected 9.4 million customers and eroded confidence in the company.

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The Royal Mail share price nosedived in late September following a shock profit warning, and has fallen from £4.55 at the beginning of January to £3.50.The British postal and courier service, which was privatised in 2013, is suffering from sluggish productivity and a steep decline in letter volumes.

The share price of French retail group Casino Group, which owns supermarket brands around the world, fell to a 22-year low in August and is currently trading at €39 (US$44.60/£34.25), down from €51.10 (US$58.44/£44.87) at the start of the year. An analyst review of the company's joint-venture transactions exposed debt concerns that have worried investors, hence the precipitous drop.

Lacklustre sales in China and, to a lesser extent Europe, have eaten into Ford's profits big-time in 2018, smashing the American automaker's share price, which fell to its lowest level in nine years on 24 October, and has only marginally recovered to hit $9.44 (£7.25), down from $12.66 (£9.72) at the start of 2018.

Harley-Davidson is having a horrendous year with its share price trading near a seven-year low, down from $52.06 (£39.97) at the beginning of January to $38.49 (£29.55). Trump administration tariffs have pushed up costs, and moved some production overseas, and sales have slipped as the iconic motorcycle manufacturer struggles to attract younger customers. 

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Down from €70.62 ($80.78/£62.03) at the start of the year to €52.40 ($59.94/£46.02), Daimler stock fell sharply in October after the German carmaker issued a profit warning, spooking investors. The unexpected drop in profits has been put down to the cost of recalling vehicles with diesel defeat devices and banned air con fluid, as well as slowing Mercedes sales in Germany.

On 24 October, South Korean automaker Hyundai Motor Company reported a 67% plunge in profits for the third quarter of 2018, and its share price has flopped accordingly, down from ₩150,500 (US$135/£103.67) at the start of the year to ₩106,500 (US$95.55/£73.36). A slowdown in sales in China is one of the factors behind the drop in profits and stock price.

Vancouver-based, New York-listed gold production company Goldcorp has had a dire year to date as output from its key Mexican mine has decreased and costs have risen. As might be expected, the Canadian mining firm's share price hit a 16-year low in October, and is currently trading at US$9.10 (£6.99), down from US$13.22 (£10.15) at the start of January.

One of America's leading food and drinks companies, Dean Foods is not in the best of shape. Its share price hit a 21-year low in October, and is trading right now at $7.95 (£6.10), down from $11.44 (£8.78) at the beginning of the year. Flagging demand for the firm's dairy products, strong competition and higher tariff-related costs are doing the company zero favours.

Down from €101.36 (US$115.97/£89.01) at the start of 2018 to €67.71 (US$77.47/£59.46), shares in German pharmaceuticals giant Bayer have been falling since August when a Californian jury awarded $289 million (£222m) to former school groundskeeper Dewayne Johnson, who claimed that glyphosate, the key ingredient in Roundup weedkiller, caused his terminal cancer. Bayer acquired Monsanto, the controversial US firm that makes Roundup, earlier this year and now faces a tidal wave of related lawsuits. 

A surprise profit warning issued earlier this month sent shares in the UK's Keller Group, the world's largest geotechnical contractor, into freefall. The construction titan's stock is trading at £6.47 currently, down from £9.69 at the beginning of January, a fall of just under a third.

The world's largest PR and ad agency, Britain's WPP has seen its share price plunge this year, down from £13.36 at the start of 2018 to £8.88. Several factors are behind the fall, including the abrupt departure of company founder and CEO Martin Sorrell (pictured) in April, the weak pound and a slowdown in business in the US.

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US retailer Bed Bath & Beyond has been losing customers to competitors such as HomeGoods and Target, and profits have gone seriously south this year, along with the homeware chain's share price, which slumped to an 18-year low in September. it is now trading at $13.98 (£10.74), down from $22.29 (£17.12) at the beginning of 2018.

Private hospital group Mediclinic International, which operates in Africa, the Middle East and Europe, warned investors earlier this month of an 8% fall in profits due to tightening regulation in the UK and Switzerland. Shares in the London-listed firm have dipped to a record low as a consequence, down from £6.49 at the start of the year to £3.77.

Mired in debt, Rite Aid has hit rock-bottom since its proposed merger with rival chain Albertson was scuppered by activist shareholders. Shares in the US drugstore company fell to a six-year low in October and are currently trading at $1.20 (£0.92), down from $2.13 (£1.64) at the beginning of the year.

A succession of bad news, culminating in reports of a major gas turbine failure in Texas, has pummelled the GE stock price, which has been on a downward trajectory, falling from $17.98 (£13.81) at the start of 2018 to $9.90 (£7.60). In fact, GE shares haven't been this cheap since the aftermath of the global financial crisis in 2009.

After reporting a profit loss of 65% for Q3, German banking behemoth Deutsche Bank saw its share price crash to a record low on 26 October, and has since recovered only slightly. Down from €15.96 ($18.27/£14.03) at the beginning of January, the current price is just €8.69 ($9.95/£7.64).

Shares in Australia's largest wealth management firm AMP are trading at a 15-year low currently, down from AU$5.19 (US$3.76/£2.88) at the beginning of the year to AU$2.47 (US$1.79/£1.37). In April, the banking Royal Commission revealed AMP had engaged in corporate cover-ups and lied to regulators. Since then, clients have been deserting the firm in their droves.

Toronto-headquartered retailer Roots Canada has had a rough one so far this year. The chain, which has locations in North America and Asia, reported disappointing financials in September as sales have fallen away, and the firm's share price tumbled to a record low on 24 October. It has only slightly recovered to hit CA$5.18 (US$3.96/£3.04), down from CA$11.22 (US$8.59/£6.59) at the start of 2018.

Shares in Taiwanese tech company HTC have been falling in price since 2011, dropping to a record low in October, down from NT$73.90 (US$2.43/£1.86) at the beginning of January. The current price is just NT$33.60 (US$1.10/£0.85). Amid intense competition, sales of the firm's smartphones and other devices fell by 81% in September compared to the same time last year.

Snapchat lost two million users in the third quarter of this year and, despite reporting better than expected earnings, parent company Snap Inc. has got investors rattled. This is reflected in the stock price, which is down a staggering 76% since the IPO in March 2017, and has fallen from $14.95 (£11.48) at the start of 2018 to $6.52 (£5.01).

Shares in India's Tata Motors, which is listed on the Bombay Stock Exchange (BSE), have taken a battering this year, down from ₹424.55 (US$5.86/£4.50) at the start of January to ₹178.65 (US$2.46/£1.89). The culprit? Poorly-performing Tata subsidiary Jaguar Land Rover, which is grappling with slowing sales in China, the shift away from diesel and the threat of a hard Brexit.

British streetwear retailer Superdry downgraded its profit forecast for 2018 by £23 million in mid-October due to poor sales over the summer and a misjudged currency hedge. This profit downgrade has hammered the company's share price, which is now trading at £8.04, down from £19.80 at the start of the year.

The JCPenney share price is now in uncharted territory, having fallen to its lowest level since the Great Depression, down from $3.50 (£2.69) at the start of January to $1.40 (£1.08). The floundering US retailer, which closed eight stores this year, is trying to keep its head above water as sales continue to fall and losses mount up.

Shares in Massachusetts-based Merrimack Pharmaceuticals have dropped to a near-record low of $3.95 (£3.03), down from $10.65 (£8.18) at the beginning of the year. The clinical-stage oncology company recently announced it had canceled a phase two trial of a combination drug treatment for lung cancer, which explains the plunge.

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After going public in June 2017, New York-based meal kit service Blue Apron has performed abysmally. Stiff competition from the likes of Walmart and Amazon, and a significant drop in customers during the second quarter of this year, have wiped 85% off the value of the company's stock since its IPO. The price is currently $1.40 (£1.08), down from $4.10 (£3.15) at the start of 2018.

The UK's Debenhams department store chain has endured an annus horribilis so far. The ailing business posted losses of £492 million in October, the greatest in its 240-year history, and is planning to close 50 stores. Needless to say, the company's share price has bombed, down from £3.51 at the beginning of the year to just 8p.

Europe's largest zinc smelter, Belgium-based metals firm Nyrstar is in big trouble. The Euronext-listed mining company, which has been plagued by low zinc prices, is valued at €169 million ($193m/£148.6m), yet its net debt is an eye-watering €1.2 billion ($1.37bn/£1.05bn). It's no wonder then that the firm's share price has hit record lows, down from €6.86 ($7.85/£6.03) at the start of the year to €1.56 ($1.79/£1.37).

Recently delisted from Nasdaq, Sears stock is now worth a humiliating 19 cents (£0.15), down from $3.78 (£2.90) at the start of 2018. This year's biggest loser, the struggling US retailer filed for bankruptcy protection earlier this month and is closing 140 stores on top of the hundreds that have already been shuttered.