The board of directors at Twitter has been shaken up. Two high-profile investors Bijan Sabet and Fred Wilson are leaving the company board of directors. Twitter’s chief scientist Abdur Chowdhury is also stepping down.

When Sarah Lacy interviewed Spark Capital partner Bijan Sabet about the danger of venture capital firms investing in similar companies, she indirectly found out about some drama between Tumblr and BNTER after doing some follow-up investigation. Lacy found out from three sources that Spark Capital had reneged on a term sheet that was offered to BNTER, a start-up based in New York founded by Lauren Leto.

Earlier this month I wrote about how YouTube was considering to buy out viral video production company Next New Networks. It turns out that in the middle of these talks, Next New Networks raised $1 million in debt financing according to an SEC filing. Some of the investors in this round include Ross Levinsohn (Fuse Capital), Bijan Sabet (Spark Capital), Saban Capital Group, and Goldman Sachs. [TechCrunch]

Spark Capital is a Boston, MA based venture capital company that invests in companies during early-stage. Spark was an early investor in 5Min Media, Tumblr, Boxee, and Twitter. When Spark invested in Twitter for a Series B round in 2008, partner Bijan Sabet joined Twitter’s board of directors. [BusinessInsider]