  Ananyevsky has recently computed the stable operations and cooperations of
rational Witt theory. These computations enable us to show a motivic analog of
Serre's finiteness result:
  Theorem: Let $k$ be a field. Then $\pi^{\mathbb{A}^1}_ n(\mathbb{S}^- _k )_*$
is torsion for $n > 0$.
  As an application we define a category of Witt motives over $k$ and show that
rationally this category is equivalent to the minus part of $SH(k)_\mathbb{Q}$.
