SAO PAULO (Reuters) -Shares of Brazilian planemaker Embraer fell sharply on Thursday after U.S. President Donald Trump said he would impose a 50% tariff on all imports from the South American country.

Analysts warned that the world's third-largest aircraft manufacturer, which has a huge market in the U.S. for its executive planes and regional jetliners, would be one of the firms most affected by the tariffs.

Sao Paulo-traded shares of Embraer tumbled as much as 8% on the news, before paring some losses to trade down 5%. Embraer was the biggest decliner on Brazil's Bovespa benchmark stock index, which slipped 0.7%.

Embraer's E1 jets are the backbone of U.S. regional aviation, with SkyWest having recently placed a firm order for 60 E175 aircraft. Demand has also been strong for its business jets in the country, where it has assembly lines. 

Itau BBA analysts said 60% of Embraer's revenues come from North America, of which three-quarters could be exposed to tariffs. They estimated a potential impact of $150 million to Embraer's earnings before interest and taxes (EBIT) from August to December.

Aircraft are among the top U.S. imports from Brazil, along with oil, steel products, coffee and orange juice.

"Although we see Trump's announcement primarily as a bargaining leverage, we expect investors' concern to remain high given the significant potential impact that a 50% import tariff on Brazilian goods would imply for Embraer," XP analysts said.

The assembly of Embraer's business jets is finished in Florida, but part of the content for those planes comes from Brazil, they noted. The tariffs could also impact demand for E1 jetliners amid an inflationary environment for the aircraft, XP added.

Embraer's shares are still up more than 30% on a year-to-date basis, following a 150% surge last year. They hit a record high earlier this month, buoyed by robust global demand for the firm's aircraft.