Platform companies such as ArQule Inc., which rely on partnerships with clients for their income, base their revenue growth expectations on the numbers of new deals they are likely to sign. These expectations are the basis for guidance to analysts, finding their way into the projections distributed on the Street.

However, predicting the certainty and timing of deals is probably even less certain than forecasting product milestones, a problem that caused ARQL last week to announce that it expects 1998 revenues to fall short of projections mainly as a result of "temporary delays by a major collaborator in starting new programs" and "the timing of initiating new major pharmaceutical company collaborations."