Mark Sierra is a Fractional CFO at Cybersecurity startup in Stealth. He possess expertise in start ups, financial modeling, mergers and acquisitions, corporate finance, finance and 24 more skills. Colleagues describe him as "Mark created one of the best financial models that I have ever seen, but what was more impressive than that was that he actually had all that information in his head. Amazing (and very useful)! Not only was Mark incredible at understanding the financial metrics for Apple, but his energy and personality just overflow to everyone around him. I think I was about 34% more effective just because I sat next to Mark. He is very fun to work with and easy to be around."