how to rotate a 3d instance using an HLSL shader

ok, im experimenting a little with HLSL shaders, i have the following code for a vertex shader, it is used to render a few instances of a 3d model. Let's say i want to rotate these instances on their Y axis, and i want to do it INSIDE the shader, is it possible? I cannot find any documentation about this.

Here it is my code:

UPDATE: i modified the code so that now the shader receives a rotation parameter instanceRotation (in radians) and use the instanceRotation.y to create a matrix to rotate the object instance around the y axis. It looks like it works, i leave it here in case anybody needs it.

/////////////
// GLOBALS //
/////////////
cbuffer MatrixBuffer
{
    matrix worldMatrix;
    matrix viewMatrix;
    matrix projectionMatrix;
};


//////////////
// TYPEDEFS //
//////////////
struct VertexInputType
{
    float4 position : POSITION;
    float2 tex : TEXCOORD0;
    float3 normal : NORMAL;
    float3 instancePosition : TEXCOORD1;
    float3 instanceRotation : TEXCOORD2;

};

struct PixelInputType
{
    float4 position : SV_POSITION;
    float2 tex : TEXCOORD0;
    float3 normal : NORMAL;
};


////////////////////////////////////////////////////////////////////////////////
// Vertex Shader
////////////////////////////////////////////////////////////////////////////////
PixelInputType LightVertexShader(VertexInputType input)
{
PixelInputType output;


// Change the position vector to be 4 units for proper matrix calculations.
input.position.w = 1.0f;


matrix <float, 4, 4> translation =
{
    1.0f, 0.0f, 0.0f, 0.0f,
    0.0f, 1.0f, 0.0f, 0.0f,
    0.0f, 0.0f, 1.0f, 0.0f,
    input.instancePosition.x, input.instancePosition.y, input.instancePosition.z, 1.0f

};

matrix <float, 4, 4> rotationAroundY = {
               cos(input.instanceRotation.y), 0.0f, -sin(input.instanceRotation.y), 0.0f,
               0.0f, 1.0f, 0.0f, 0.0f,
               sin(input.instanceRotation.y), 0.0f, cos(input.instanceRotation.y), 0.0f,
               0.0f, 0.0f, 0.0f, 1.0f   
                           };

matrix <float, 4, 4> composition;

//i compose together the rotation around y and the translation, the order is important!
composition = mul(rotationAroundY,translation);
//i apply the transformation to the vertex input.position
output.position = mul(input.position,composition);


// Calculate the position of the vertex against the world, view, and projection matrices.
output.position = mul(output.position, worldMatrix);
output.position = mul(output.position, viewMatrix);
output.position = mul(output.position, projectionMatrix);

// Store the texture coordinates for the pixel shader.
output.tex = input.tex;

// Calculate the normal vector against the world matrix only.
output.normal = mul(input.normal, (float3x3)worldMatrix);

// Normalize the normal vector.
output.normal = normalize(output.normal);

return output;

}