Exhibit 99.40 MBNA MASTER CREDIT CARD TRUST II SERIES 1999-E KEY PERFORMANCE FACTORS April 30, 2000 Expected B Maturity 6/17/02 Blended Coupon 6.3128% Excess Protection Level 3 Month Average 5.85% April, 2000 5.49% March, 2000 5.89% February, 2000 6.18% Cash Yield18.08% Investor Charge Offs 4.70% Base Rate 7.89% Over 30 Day Delinquency 4.72% Seller's Interest10.74% Total Payment Rate13.82% Total Principal Balance$52,271,464,953.72 Investor Participation Amount$1,000,000,000.00 Seller Participation Amount$5,612,664,435.23