Boeing Co said on Monday it would raise its quarterly dividend by 20 per cent and replace its existing share buyback program with a new US$18 billion authorization.

The company's shares, the best-performing Dow component this year with an 84 per cent surge, were up 1.2 per cent at US$286.51 in after-market trading.

The world's biggest maker of jetliners said the raised dividend and the new buyback program were not in response to a Republican tax overhaul, which seeks to cut corporate taxes to 20 per cent from 35 per cent.

Other U.S. corporations have said they would use the windfall from the tax overhaul to buy back shares, retire debt and other shareholder-friendly moves.

The cash deployment plans reflect ongoing confidence in our financial strength and the long-term outlook of our business, Boeing Chief Financial Officer Greg Smith said in a statement.

Boeing's dividend increase comes at the high-end of analysts' estimates of 15 per cent to 20 per cent, Robert W Baird & Co analyst Peter Arment wrote in a note.

The company said on Monday the new quarterly dividend would be US$1.71 per share, up from US$1.42.

Boeing said the new repurchase program would replace a US$14 billion authorization approved in December 2016, under which the company had repurchased US$9.2 billion.

The increase in the buyback amount also comes as a surprise and shows the management's confidence in generating strong free cash flows over the next few years, analyst Arment said.

Boeing said it expected to complete the new buybacks in the next 24-30 months.