Swiss agrochemicals giant Syngenta on Thursday moved to placate shareholders after it rejected a massive takeover bid by Monsanto, announcing it would sell its vegetable seed business and buy back $2.0 billion worth in shares.

Syngenta, which last week saw its share price plunge 18 percent after US seed giant Monsanto finally dropped its campaign to buy it, said Thursday it would take a series of measures to "accelerate shareholder value creation".

The divestment of its global vegetable seed division was part of this plan, it said, pointing out that the business had "a significant global footprint and a wide array of best-in-class varieties," adding that it was "expected to attract significant third-party interest."

The unit raked in $663 million in sales last year.

Syngenta said it also aimed to return "significant levels of capital" to its shareholders through a programme to buy back more than $2.0 billion in shares, set to begin in coming weeks.

"The board and management are determined to accelerate shareholder value creation and our actions today underpin our commitment to do so," chairman Michel Demare said in a statement.

Last week, Syngenta saw its share price plummet after Monsato dropped its campaign to buy the company, maintaining it had no choice but to pull the plug on the proposed deal after Syngenta refused to entertain repeated and improved offers.

The last bid, proposed on August 18, worth about $46 billion at the time, would have amounted to 470 Swiss francs per share overall, up from the original April bid of 449 francs per share, Monsanto said.

"Syngenta management reacted well to appease shareholders after the failed takeover by Monsanto," IG analyst Andreas Ruhlmann said in a note.

He pointed out that Monsanto had planned to sell off the vegetable seed division, which accounts for 21 percent of Syngenta's business, if the takeover deal had gone through.

And, he stressed, although the seed business had been undergoing difficulties for the past two years, "the potential for margin expansion should not fail to attract buyers."

"This move makes sense, as it will allow Syngenta to concentrate on its high margin crop business where it enjoys a world leading position," he said.

Many analysts downgraded Syngenta after the Monsanto deal fell through, but Ruhlmann said Thursday's announcement "leaves a lot of room for any upside surprise."

"And if Syngenta successfully sells its seed branch, there are chances Monsanto will come back with yet another offer," he added.

Following Thursday's announcement, Syngenta saw its share price rise 3.36 percent in midday trading to 337.90 Swiss francs a piece, as the Swiss stock market's main SMI index rose 1.63 percent.