It is the issue of new fully paid-up shares to existing shareholders on a pro-rata basis. The impact of a bonus issue is to reduce the share price as the same market capitalisation of the company is spread over a larger number of shares, which in turn benefits the liquidity of the scrip. London Stock Exchange Glossary
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bonus shares UK US noun [plural] FINANCE, STOCK MARKET
► payment of part of a company’s profits to shareholders in the form of extra shares rather than dividends: »
He received £424,000 of bonus shares relating to the Freeserve sale.
Financial and business terms. 2012.