Brian Dress, director of research for Left Brain Investment Research, says that the market's recent machinations raises questions about the environment for growth and the changing spectrum of opportunities, and that it encourages investors to protect and/or take profits, but he says that investors should hold fast to core positions -- for Left Brain that's stocks like Nvidia and Roku -- where the growth story is intact so that being swayed by short-term fluctuations will only lead to bigger regrets and smaller profits in the future.