http://money.com/money/5267940/companies-spending-trump-tax-cuts-stock-buybacks
"Here are some of the biggest stock buyback announcements so far in 2018, according to Kiplinger.
Apple – $100 billion
Cisco – $25 billion
Wells Fargo – $22.6 billion
Pepsi – $15 billion
AbbVie – $10 billion
Amgen – $10 billion
Google parent Alphabet – $8.6 billion
Visa – $7.5 billion
eBay – $6 billion
Investors can expect even bigger buybacks after the first half of the year ends, says Silverblatt."
Microsoft is also buying back shares:
https://www.fool.com/investing/2018/12/30/3-tech-companies-that-are-spending-billions-to-buy.aspx
Amazon is not buying back shares.