Peter Weill's produced a study that identified the $4$ main categories that make up a company's IT portfolio: the IT infrastructure, transactional systems, informational systems, and strategic systems. Weill's research shows that most companies spend a majority of their IT portfolio on the $1.\_\_\_\_\_\_$ and the least amount of money is spent on the $2.\_\_\_\_\_\_\_\_\_\_.$ A company that is seeking to be highly agile should spend more money on the $3.\_\_\_\_\_\_\_\_\_\_$ to provide a nimble platform and less money on the $4.\_\_\_\_\_\_\_\_\_,$ which tends to lock in current business processes.