Sept 18 (Reuters) - The Russell 2000 index notched a

record-high close on Thursday for the first time in four years,

reflecting growing optimism about small-cap U.S. companies as

lower interest rates boost investor confidence.

The index gained 2.5% for the session to close at

2,467.70, eclipsing its previous all-time high close of 2,442.74

reached in November 2021.

The Russell 2000 is made up of about 2,000 publicly

listed companies that are smaller than those included in the S&P

500. It has soared about 40% since April 8, the low point

of a global selloff fueled by worries about President Donald

Trump's sweeping tariffs.

"Small caps have underperformed pretty dramatically over the

last decade or so, and catch-up trade seems to be underway. ...

We see the environment that we are in being conducive for the

rally in small caps to continue," said Keith Buchanan, senior

portfolio manager at Globalt Investments.

The index has rebounded, along with the benchmark S&P 500

and the blue-chip Dow Jones Industrial Average, as a

limited effect of tariffs on U.S. inflation and Washington's

deals with major trading partners eased investors' worries.

Anticipation ahead of the Federal Reserve's 25-basis-point

interest rate cut last Wednesday fueled recent gains in the

Russell, along with expectations of additional rate cuts before

year-end. Small-cap companies are more reliant than larger

corporations on debt financing, and they tend to benefit from

low interest rates.

Trump's sweeping tax cut bill, passed by the Senate in

July, will also support domestically driven small caps more than

multinational corporations, Buchanan also said.

The Russell 2000 index has gained about 11% so far this

year, lagging the S&P 500, which has gained about 13%.