StackOverflowException - query result set is too big?

Question

My query below checks through over 2000 categories categoriesToCheck and find articles within those categories. I guess it is too big to add to a generic list?

I'm getting an error from this line below listInitialResult.AddRange(queryableInitialResult.ToList());

namely:

An unhandled exception of type 'System.StackOverflowException' occurred

I hope anyone can suggest a good way of doing this.

if (categoriesToCheck != null && categoriesToCheck.Count() > 0)
{
    var searchPredicate = PredicateBuilder.False<T>();

    foreach (ID category in categoriesToCheck)
    {
        var categoryToCompare = category.ToString().Replace("{", "").Replace("}", "");
        searchPredicate = searchPredicate.Or(i => i.Tags.Contains(categoryToCompare));
    }

    queryableInitialResult = queryable.Where(searchPredicate);

    listInitialResult.AddRange(queryableInitialResult.ToList());
}