This paper examines the effect of concurrent capital expenditure on the market reaction to corporate alliance announcements. Based on a large sample of announcements made in the UK between 1993 and 1995, the evidence suggests that the market response is most favourable when new investment does not form part of the joint activity. The results also suggest that the decision to formalize the partnerships through the establishment of a joint venture impacts negatively on announcement period share returns. The findings are shown to be consistent with a scenario whereby the market response reflects concern about the dangers of overly-committed partnerships.