The move adds to a large cash pile at an airline that has been less badly affected by the pandemic than many of its rivals owing to its relatively low level of debt and lack of exposure to the badly hit long-haul and business-class markets.
Ryanair issued 35,242,291 shares, about 3.2% of its total share capital, at a price of 11.35 per share. That represents a discount of roughly 2.6% to its closing price on Thursday.
The airline said it was raising the funds to capitalise on opportunities created by COVID-19 disruption and to de-risk its debt repayments over the next 12 months.
"As we look beyond the next year, we expect that there will be significant growth opportunities for Ryanair's low-cost model as competitors shrink, fail or are acquired by government bailed out carriers," the airline said.
"The placing will provide Ryanair with greater financial flexibility to capture these opportunities."
Ryanair flew a little less than half as many passengers in August than in the same month last year, but it has one of the strongest balance sheets in the industry with more than 3.9 billion euros in cash at June 30 and unencumbered Boeing 737 jets worth about 7 billion euros.
However, it also has 1.9 billion euros of debt maturing next year, including an 850 million euro Eurobond and £600 million raised under Britain's Covid Corporate Financing Facility.
Bernstein analyst Daniel Roeska on Thursday described the placement as a "small raise for a big company".
"They do not need the cash and the amounts involved are small," Roeska said. "Insulating against winter chill, defending the BBB rating and getting shareholders to show their support for the group do make sense as reasons, however, given upcoming refinancing needs."
By Conor Humphries