Shares in German sportswear firm Adidas soared today after it announced a big buyback, gave an upbeat outlook for 2018.

The company also lifted its 2020 profitability forecast, while conceding it would be hard to match rival Nike's margins. 

Adidas said last night that it plans to buy back up to €3 billion of its shares, or almost 9% of its share capital, by 2021 on top of a higher-than-expected 2017 dividend of €2.60 per share. 

The company's online sales leaped 57% in 2017 to €1.5 billion, or about 7% of sales. 

"2018 will be a good year for us, ensuring we get the right balance of market share growth and margin growth to get us closer to where some of our competitors are," chief executive Kasper Rorsted told a news conference. 

After a tough few years, Adidas has returned to form under Rorsted, taking market share from bigger rival Nike in North America and selling its underperforming TaylorMade golf and CCM Hockey brands. 

Since taking over in 2016, Rorsted has put a sharper focus on improving profitability, which still lags Nike. 

Finance chief Harm Ohlmeyer, who used to lead the Adidas ecommerce business, told the news conference it would be hard to close the gap completely given Nike's dominance of the US market, but he said online sales were helping margins.

Rosted said there was still huge potential to increase online sales further given that ecommerce accounts for about 15-20% of sales for the global sporting goods market.

Adidas forecast currency-neutral sales would rise around 10% in 2018, with an operating margin of between 10.3% and 10.5%, up from 9.8% in 2017. 

Nike reported an operating margin of 13.8% for its 2016/17 fiscal year.

Adidas said it expects a boost from the 2018 soccer World Cup, although Rorsted noted that the event has less impact than before as soccer now accounts for less than 10% of sales. 

He said the company had no plans to boycott the tournament despite rising political tension between the West and Russia: "Isolation is not the best way to resolution," he said. 

Adidas lifted its forecast for the operating margin to hit 11.5% by 2020, up from a previous forecast of 11%. 

Rorsted highlighted steps to improve efficiency, such as more global purchasing, shared business services and fewer products. 

Fourth-quarter sales rose 12% to €5.06 billion, missing analyst forecasts for €5.13 billion as sales in Russia and at its Reebok brand slipped. 

It reported operating profit more than tripled to €132m, beating analyst forecasts for €61m, but recorded a net loss of €41m after a tax impact of €76m due to changes in the US tax code. 

Rorsted said a turnaround plan he launched for loss-making Reebok was bearing fruit, with the brand expected to return to growth in North America in 2018.