During the The Child of Daralet event (Upcoming Fellowship Changes 2000/12/07), a bonus was added to fellowship experience. This provides an incentive to hunt together as a fellowship. This option may be turned off by unchecking the Share XP option in the Fellowship panel. The table below gives the amount of xp each member will receive as well as the "extra" xp generated by the bonus. See also Coordinating a Fellowship.

Number
in Fellow
Member
Share
XP
Bonus
1 100% 0%
2 75% 150%
3 60% 180%
4 55% 220%
5 50% 250%
6 45% 270%
7 40% 280%
8 35% 280%
9 30% 270%

For example, if three people each killed 1 creature worth 100,000xp and they were not in an xp sharing fellowship, they would each earn 100,000xp. If however they formed a fellow and each killed 1 creature, they would each earn 60% of all three kills, or 180,000xp.