New Bound States of several Top-quarks bound by Higgs Exchange
  It is suggested that there is a fine tuning principle remarkably arranging the top-quark Yukawa coupling to be just so as to make the mass $m_{12}$ of a bound state of 6 top + 6 anti-top quarks become very small. The value of the top Yukawa needed for Higgs and gluon etc. exchanges just binding the 12 quarks to make this mass zero is $g_t|_{m_{12}=0} =1.01 \pm 0.15$, while the experimental running top Yukawa coupling is $g_t = .94$. 
C. D. Froggatt and H. B. Nielsen