Amazon increased the threshold needed for non-members to qualify for free shipping as it seeks to add more people to its $99 annual Prime loyalty program.
Non-members must now spend a minimum of $49, up from $35, to get free shipping. Members don't have a minimum.
The Seattle company has long invested huge sums of money back into its businesses, particularly by expanding perks for Prime members. That includes one-hour delivery in some cities, beefed up video streaming and free e-books.
Investors, however, have grown impatient with some of those programs, which can cut into profits.
After the company boosted the minimum for non-member free shipping, shares of Amazon.com Inc. jumped 4 percent, the largest increase on the S&P 500 index.