The number of mid-sized companies in Canada declined by 17 per cent from 2006 to 2010, according to a study by the Business Development Bank of Canada.

It says the number dropped from 9,370 to 7,814 during that period.

The study says the hardest hit sector was manufacturing, which saw more than half its mid-sized firms vanish between 2001 and 2010 from 2,807 to 1,381. The BDC study is based on Statistics Canada data and Harris-Decima surveys.

It also found that 14 per cent of mid-sized firms became small firms (below 100 employees) or closed down each year from 2006 to 2010.

Only 1.4 per cent grew to become corporations with 500 or more employees.

While mid-sized companies declined across the country, Ontario was hit worst, losing a quarter of these firms between 2006 and 2010 (from 3,810 to 2,861).

"This decline should signal a call to action as mid-sized firms are vital to the Canadian economy," said BDC chief economist and study lead author Pierre Cleroux.

"They're few in numbers, yet their contribution to Canada's economic prosperity cannot be overemphasized. They really do punch above their weight."

BDC said while mid-sized firms represent just one per cent of the total number of companies, they account for 16 per cent of Canadian jobs, 12 per cent of GDP and 17 per cent of exports.