X0304 4 2012-02-23 0 0001093649 IDENIX PHARMACEUTICALS INC IDIX 0001114448 NOVARTIS AG LICHSTRASSE 35 BASEL V8 CH4002 SWITZERLAND 0 0 0 1 Indirect 10% Owner 0001030617 NOVARTIS PHARMA AG LICHSTRASSE 35 BASEL V8 CH4002 SWITZERLAND 0 0 1 0 Common Stock 2012-02-23 4 P 0 35735 2.41 A 33271516 I See Footnote Common Stock 2012-02-23 4 P 0 366 2.47 A 33271882 I See Footnote Common Stock 2012-02-23 4 P 0 2493 2.56 A 33274375 I See Footnote Common Stock 2012-02-23 4 P 0 997 2.69 A 33275372 I See Footnote Common Stock 2012-02-23 4 P 0 997 2.78 A 33276369 I See Footnote Common Stock 2012-02-23 4 P 0 1321 2.85 A 33277690 I See Footnote Common Stock 2012-02-23 4 P 0 3117 2.90 A 33280807 I See Footnote Common Stock 2012-02-23 4 P 0 8960 2.96 A 33289767 I See Footnote Common Stock 2012-02-23 4 P 0 427 2.97 A 33290194 I See Footnote Common Stock 2012-02-23 4 P 0 232 3.04 A 33290426 I See Footnote Common Stock 2012-02-23 4 P 0 4336 3.17 A 33294762 I See Footnote Common Stock 2012-02-23 4 P 0 3093 3.79 A 33297855 I See Footnote Common Stock 2012-02-23 4 P 0 39 5.10 A 33297894 I See Footnote Common Stock 2012-02-23 4 P 0 11433 5.11 A 33309327 I See Footnote Common Stock 2012-02-23 4 P 0 7402 5.46 A 33316729 I See Footnote Common Stock 2012-02-23 4 P 0 883 5.79 A 33317612 I See Footnote Common Stock 2012-02-23 4 P 0 436 5.80 A 33318048 I See Footnote Common Stock 2012-02-23 4 P 0 493 6.52 A 33318541 I See Footnote Common Stock 2012-02-23 4 P 0 2133 7.39 A 33320674 I See Footnote These securities are owned directly by Novartis Pharma AG, a direct, wholly-owned subsidiary of Novartis AG. Novartis AG is indirect beneficial owner of these securities. See attachment. /s/ Marc Ceulemans, Head Strategic Venture Capital Fund & Pharma Equities 2012-02-23 /s/ Felix Eichhorn, Authorized Signatory 2012-02-23