5 THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE UNAUDITED FINANCIAL STATEMENTS OF NETWORK-1 SECURITY SOLUTIONS, INC. FOR THE PERIOD ENDED SEPTEMBER 30, 1999 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS 3-MOS DEC-31-1999 JUL-01-1999 SEP-30-1999 1,319,000 0 400,000 104,000 2,000 1,884,000 1,284,000 651,000 3,419,000 995,000 0 0 6,000 44,000 2,374,000 3,419,000 186,000 1,357,000 440,000 1,620,000 4,961,000 10,000 0 (5,100,000) 0 (5,100,000) 0 0 0 (5,100,000) (1.17) (1.17)