Large cap Internet stocks have performed well in 2015, but nearing the end of the year, it's important to re-evaluate where they're headed.
"It becomes really hard to say, 'Wow it's not going to keep working into next year,' even though we all know that usually the things that work this year don't work next year," said Heath Terry, head of Internet equity research at Goldman Sachs.
Terry told CNBC's "Squawk Alley" it's easy to say that valuations have to stretch when looking at individual names that have carried the market. However,Terry said investors actually need to break stock performance down into components.
"Do you really not want to continue to own Amazon with the growth that you've got in [Amazon Web Services]? Do you really not want to continue to own Facebook with the momentum that they have from advertisers? Do you really not want to own Netflix with the incredible subscriber momentum that they've got?" he asked.