Exhibit 99.40 MBNA MASTER CREDIT CARD TRUST II SERIES 1999-A KEY PERFORMANCE FACTORS May 31, 1999 Expected B Maturity 2/17/2004 Blended Coupon 5.1803% Excess Protection Level 3 Month Average 5.58% May, 1999 7.55% April, 1999 3.61% March, 1999 N/A Cash Yield19.45% Investor Charge Offs 4.88% Base Rate 7.02% Over 30 Day Delinquency 4.89% Seller's Interest 6.97% Total Payment Rate14.69% Total Principal Balance$41,914,776,221.36 Investor Participation Amount$500,000,000.00 Seller Participation Amount$2,922,256,702.87