By Anastasija Johnson

NEW YORK, April 18 (Reuters) - U.S. high-grade corporate bond issuance hit a record in April as companies took advantage of improving market sentiment and strong investor demand for new deals.

U.S. investment-grade corporate bond volume totaled $50.7 billion through April 18, according to research firm Dealogic. The previous record for this month was in April 2001, when companies sold $47.35 billion of high-quality debt.

This week's issuance alone included a few marquee deals from a finance subsidiary of General Electric Co (GE.N: Quote, Profile, Research), JPMorgan Chase & Co (JPM.N: Quote, Profile, Research), XTO Energy (XTO.N: Quote, Profile, Research) and Lehman Brothers (LEH.N: Quote, Profile, Research).

General Electric Capital Corp's $8.5 billion transaction was the fifth-largest U.S. corporate bond sale since 1995.

Despite its jumbo size, the deal was oversubscribed and bonds traded up in the secondary market, prompting other issuers to follow suit, said Jim Merli, managing director and global head of fixed income syndicate at Lehman Brothers, the lead bookrunner on GE Capital's deal.

"The market has a way of being self-fulfilling," Merli said. "The market felt better, therefore GE decided to do their transaction. The GE deal went so well that the market continued to improve and more clients decided to move forward with their deals. It feeds on itself."

The credit market sentiment has been improving since late March after the Federal Reserve helped JPMorgan buy Bear Stearns & Co BSC.N to save it from collapsing.

The Fed's decision to give brokers the same access to liquidity that it provides commercial banks added weight to investors' viewpoint that the worst part of the credit crisis is over.