Banks have not yet reaped the full benefit of U.S. tax cuts, Wall Street executives said on Friday after a string of quarterly results, tempering earlier expectations that lower rates would quickly create an investment boom and stimulate business growth.

Analysts and investors are still trying to work out the longer-term effects of the tax rewrite signed into law in December, which slashed the corporate rate.

That showed executives are hesitant to put a timeframe on when they will see the economic growth, consumer spending and stronger corporate lending they flagged last quarter as a result of the tax cuts.

"As much as we’re all eager to see the benefits ... I think we have to recognize that tax reform is still in the early phases,” JPMorgan Chase & Co. Chief Financial Officer Marianne Lake said on a media conference call after the bank reported first-quarter results.

She told reporters earlier that “optimism does continue to be very high,” and that JPMorgan expects to see benefits, but “with a lag.” The largest U.S. bank by assets narrowly missed analyst estimates, due in part to weaker investment banking revenue.

"While client sentiment is high in the wake of corporate tax reform and we remain hopeful that this will support higher demand later in the year, we're not seeing that yet, and we are maintaining pricing and credit discipline," Lake said about loan demand.

Financial markets have already reflected investors' enthusiasm about the cuts, Citigroup Inc. Chief Financial Officer John Gerspach said on a call with reporters to discuss quarterly results, and the actual benefit to the U.S. economy will only come once investment plans are finalized.

"A lot of corporate actions are in the planning stage. People usually have nine to 12 months to plan for tax reform. People had a chance to digest this right around the last three weeks of last year," Gerspach said. "I actually think the best is yet to come."

A cut in the federal corporate tax rate to 21 percent from 35 percent has helped banks boost profit, but other details of the new tax code has not helped their bottom line.

Wells Fargo & Co. said its interest income slipped 1 percent in the first quarter due in part to lower income from so-called tax-advantaged products in light of newly lowered tax rates.

Lower tax-equivalent yields on municipal bonds should weigh on year-over-year comparisons of the lender's net interest margin by around 4 basis points for the rest of the year, Chief Financial Officer John Shrewsberry said on an analyst call.

The third-largest lender by U.S. assets also flagged that tax changes had weighed on new debt issuance and secondary trading, though strong equity trading helped boost its total trading-related revenue.