Chief Executive Officer of Amazon, Jeff Bezos, tours the facility at the grand opening of the Amazon Spheres, in Seattle, Washington on January 29, 2018.

Shares of Amazon gained nearly 4 percent Wednesday after a price target boost from Morgan Stanley, and it drove the Nasdaq 100 to an all-time high.

The e-commerce giant ended trading at $1998.10 and contributed more than 28 positive points to the market index. That beats out Apple's 14-point positive impact and Microsoft's 12-point positive impact. The index has been trading at record levels all week amid overall market gains.

Amazon stock is up 70 percent in 2018 and has more than doubled in the last 12 months.

Separately Wednesday, Amazon rejected claims by Sen. Bernie Sanders of poor worker conditions in a rare political statement for the e-commerce giant.