inline std::pair<T,T>& GetPortfolio()
{
    static std::pair<T,T> myPair;
    myPair.first = m_container.begin();
    myPair.second = m_container.end();
    return myPair;
}

std::pair<T,T> one = GetPortfolio();

//Do some algorithm on m_container

std::pair<T,T> two = GetPortfolio();

//At this point both one and two hold valid iterators (as both reference static object)