Kaledin and Verbitsky have shown that symplectic varities have a remarkably nice deformation theory *as symplectic varieties.*


Let $X$ be a symplectic variety (a smooth quasi-projective variety over $\mathbb{C}$ equipped with a nondegenerate closed algebraic 2-form $\Omega$); then there is a universal formal deformation $\tilde X$ over $H^2(X;\mathbb{C})$ completed at the class $[\Omega]$. 


In many examples, it seems that this deformation is generically affine; that is, its fiber at the generic point is an affine scheme. For example, $T^\*G/B$ deforms to a generic coadjoint orbit in $\mathfrak{g}^\*$, and if $X$ is a hyperkähler quotient, like a quiver variety, then the deformation comes from varying the complex moment map, and the deformation is also generically affine (since a GIT quotient by a free action of a reductive group is always affine).


Of course, I don't think this always happens; the product of two elliptic curves is symplectic, but doing this deformation should just change the $j$-functions of the curves simultaneously. So, clearly one needs some kind of extra condition. I've opted for "resolution of singularities of its affinization."


So my question is:



> 
> Let $X$ be a symplectic variety which is a resolution of singularities of its affinization. Is $\tilde X$ generically affine?
> 
> 
> 


**EDIT:** As was pointed out in Misha Verbitksy's answer below, the deformation is not canonically algebraic. I believe though that if you assume that $X$ has a $\mathbb{C}^\*$-action which is dilating (Definition 1.7 of [this paper](http://arxiv.org/pdf/math/0608143.pdf)), then $\tilde X$ will also have a $\mathbb{C}^\*$-action which acts by dilation on $H^2(X;\mathbb{C})$ and there will be a unique algebraic structure for which weight vectors of the $\mathbb{C}^\*$-action are algebraic functions. It is this algebraic structure I want.


**EDIT:** Since it's buried a little bit in comments, let me just put here that it's true and proven by Kaledin in [this paper](http://arxiv.org/abs/math/0312134).



Is the generic deformation of a symplectic variety affine?
Being "affine" in this case does not make much sense,
because the hyperkaehler deformation is a complex manifold, without 
a fixed algebraic structure. Simpson produced an example of a 
hyperkaehler deformation of a space of flat bundles 
admitting several algebraic structures, both
inducing the same Stein complex structure; one of them 
is affine, another has no global algebraic functions.
In fact, the space F of flat line bundles on elliptic curve 
(with an appropriate algebraic structure, defined by 
Simpson) is an example of such a manifold,
it is biholomorphic to $C^\*\times C^\*$, but 
this biholomorphic equivalence is not algebraic,
and F has no global algebraic functions.


However, you can show that a hyperkaehler deformation
of a resolution of something affine has no non-trivial complex
subvarieties (arXiv:math/0312520), except, possibly, some 
hyperkaehler subvarieties The latter don't exist, because 
the holomorphic symplectic form $\Omega$ on such a manifold
is is lifted from the base, which is affine, hence $\Omega$
vanishes on all complex subvarieties.


Therefore, a typical fiber of such a deformation is Stein. 


Indeed, a hyperkaehler deformation of a 
resolution of something affine remains holomorphically convex. To see this
if you produce a function which is strictly plurisubharmonic outside of
a compact set (we have such a function, because we started from something 
affine), and apply the Remmert reduction.


