Software development is a collective undertaking, and the team's efficiency is critical in development.
In order to reduce project management overheads and improve productivity, a global information and communication technology enterprise institutionalizes an organization wide small-team practice, called \textit{\textbf{fireteams}}, to tackle the problems arising from human and social aspects, such as amicability, talent, skill, and communications.
This paper reports a mixed-method research, which combines archive analysis, interviews and survey, to empirically investigate the characteristics and impacts of fireteam in this industrial setting.
We identify three categories of fireteam in terms of its demonstrated characteristics: ordinary agile team with extensions, single-function team, and entire life-cycle team; elaborate four key activities of fireteam, i.e. team formation, maintenance, communication, and meeting.
Less communication and management overheads, higher agility & concurrency, and improved personal ability are the three important contributors that increase the productivity of fireteams. Whereas management & leadership effort, divergent understanding of fireteam, and self-organized team are discovered as the three major problems associated with fireteams.
Although the benefits of fireteam can be observed from its adoption, this practice does not achieve the enterprise's anticipations very well. Some considerations and recommendations are also discussed to improve this small-team practice. % and adopt more innovative practices in industry.