Citadel’s Ken Griffin is optimistic on the economy for the rest of the year.

“In short run absent a material trade catastrophe [I see] very strong growth in the next six to nine months," Griffin said at the Delivering Alpha Conference in New York on Wednesday.

The investor cited how the corporate tax cut is pulling forward demand and capital expenditures. President Donald Trump signed the Republican tax overhaul in December, which lowered the corporate tax rate to 21 percent from 35 percent.

The hedge fund manager warned that after a period of strong economic growth, the long-term picture may become more difficult.

2020 is "much more murkier," he added.

Griffin founded Citadel in 1990. The investor has a net worth of $9 billion, according to Forbes. His hedge fund firm now manages more than $30 billion in assets. Also in its role as a market maker, 1 out of every 5 U.S. stocks trade through Citadel Securities on a daily basis, Griffin confirmed.

The firm’s multistrategy fund, known as Wellington, was up 1.52 percent in June and 8.79 percent during the first half of the year.