With nearly $800 million invested in the stock, Apple (AAPL - Get Report) remains David Einhorn's top investment, but he's buying up notable positions in some other companies, too.

Einhorn's Greenlight Capital added four new positions to its public equity portfolio during the fourth quarter of 2016, per 13F filings with the Securities and Exchange Commission released on Tuesday. Agribusiness is clearly on the radar, with the hedge fund disclosing new stakes in Syngenta (SYT) and Monsanto (MON) . It also disclosed fresh positions in Alcoa  (AA - Get Report) and Fred's Inc. (FRED - Get Report) .

Both agribusiness buys could also be read as M&A plays. Monsanto is currently in the midst of an acquisition by Bayer AG, and Syngenta is set to be bought by China National Chemical. Both deals are subject to regulatory approval.

Einhorn gave a presentation at the Robin Hood Investors Conference in December on Bayer's proposed $66 billion takeover of Monsanto, announced in September. He cheekily cast the merger as a love story inspired by the film "The Princess Bride."

"As with all love stories, there is conflict, and an uncertain ending. Will something get in the way of true love. Or will they consummate the marriage and live happily ever after?" he said.

Greenlight is also long German-listed Bayer.

In his 2016 letter to investors, published by ValueWalk, Einhorn provided insights not only into his latest buys and sells but also into his broader thesis on the Trump administration.

"While it's hard to know exactly where President-elect Donald Trump stands from day to day, his main economic policy objective appears to be employment," he wrote. "To that end, he has proposed corporate tax cuts, infrastructure investment, and military build-up, combined with anti-immigration policies and trade protectionism. To the extent that he can implement these policies, the economy should accelerate, and given that we are starting with less than 5% unemployment, a labor shortage could develop."

He said Trump's proposed repatriation tax holiday leaves him bullish on Apple and his focus on jobs and wages improves the outlook for General Motors (GM - Get Report) , in which Greenpoint "dramatically increased" its position.

The letter was released prior to Trump's inauguration.

This article was written by a staff member of TheStreet.