Private Provision of a Complementary Public Good

For several years, an increasing number of ¯rms are investing in Open Source Software (OSS). While improvements in such a non- excludable public good cannot be appropriated, companies can bene¯t indirectly in a complementary proprietary segment. We study this incentive for investment in OSS. In particular we ask how (1) market entry and (2) public investments in the public good a®ects the ¯rms' production and pro¯ts. Surprisingly, we ¯nd that there exist cases where incumbents bene¯t from market entry. Moreover, we show the counter-intuitive result that public spending does not necessarily lead to a decreasing voluntary private contribution.