Activist investor Jeffrey Smith had a new top holding in the third quarter
(This story is for CNBC Pro subscribers only). Activist investor Jeffrey Smith revealed the size of one of the recent bets for his Starboard Value hedge fund in a securities filing, which also showed the fund building its stake in an engineering stock. Starboard managed $5.5 billion in assets as of 2019. Here's a look at the fund's biggest holdings at the end of September, including a new top holding. The latest securities filing shows Corteva as the fund's largest holding at $337 million at the end of September. Smith revealed in early October that Starboard had taken new stakes in Corteva and ON Semiconductor , but the size of the positions was not disclosed. The agriculture company, which was spun out of DuPont in 2019, has seen its stock rise 15% since Smith made the announcement in October. The investor said that the company was "recession-resistant" and had strong growth prospects in the years ahead. The ON Semiconductor position is not shown in the filing and was likely initiated after the end of the quarter. There were no other new positions in individual stocks created during the third quarter. One of the most notable instances of Starboard adding to an investment was engineering company AECOM . The fund increased its shares in the company by 29% to make it the second-largest holding at $323.5 million. The fund also increased its stake in payments company ACI Worldwide to roughly $128.1 million, and said in a securities filing in October that it had continued to add to the position. The other stocks in the top ten individual positions for Starboard include some names that the fund has trimmed significantly. The fund's biggest holding at the end of June was NortonLifeLock . Starboard sold nearly half of its shares in the company during the third quarter, but stake was still worth $260.3 million at the end of September. Smith also sold about 40% of the fund's shares of Advance Auto Parts , but the retail stock was still Starboard's fourth biggest individual holding. Starboard exited a position in e-commerce company eBay that was worth $109.6 million at the end of the second quarter. The fund had previously sold a large portion of its stake in the company during the second quarter. Smith was also one of many high profile investors to jump in on the SPAC boom , taking a blank-check company public in September. There are no SPACs listed among the Starboard fund's holdings, however.

Jeffrey Smith, CEO and chief investment officer at Starboard Value LP. David Paul Morris | Bloomberg | Getty Images