The Relationship Between Inertial and Gravitational Mass
  I will argue that the inertial mass is greater than the gravitational mass for all objects which are held together primarily by gravitational forces. Thus, for celestial objects, like planets, stars and galaxies, their inertial mass is greater than their gravitational mass. The analysis used to arrive at this conclusion shows that there should, in principle, exist classical objects with non-zero inertial mass and vanishing gravitational mass. Implications for Quantum Gravity and Quantum Cosmology, are briefly discussed. 
Gregory W. Horndeski
physics.gen-ph