The self-described Democratic socialist isn't coy about calling out big companies on social media.
Wall Street remains concerned over how the investments will weigh on margins.
The world's largest retailer is slated to report fourth quarter earnings on Tuesday.
The world's largest retailer began bolstering its partnerships with third-party courier firms to reach consumers in 100 U.S. cities last year to better compete with Amazon.
The world's largest retailer has a lot riding on its seasonal performance.
The move comes as new e-commerce rules for the country went into effect Friday.
The retailer says it will raise driver pay to an average of about $87,500 per year.
The company said it expects to have 360 “Auto-C” robots active in stores by the end of January 2019.