Irvine-based savings and investing app developer Acorns has tapped an executive from Twitter as its new Chief Financial Officer, the company said this morning. According to Acorns, it has named Rich Sullivan as CFO, ahead of its expected public listing. Sullivan was previously head of Corporate Finance and FP&A at Twitter, and also had served at STX Entertainment and DreamWorks Animation, in addition to AT&T. Acorns said that its current CFO, Jasmine Lee--who had been both Chief Operating Officer and Chief Financial Officer--will now focus on day to day operations as COO. Acorns is in the midst of a special purpose acquisition company (SPAC) merger with Pioneer Merger Corp., which will take it to the public markets.