As it doesn`t make any economic sense, the answer has to be political, and selling these shares to private investors, when prices are almost certainly set to rise, seems a very effective way of bribing yourself back into favour with the financial sector.
What a shame the much vaunted "long-term economic plan" allows for such short-term thinking! With the OECD announcing that investment in British business is too slow, what a wonderful opportunity Osborne is wasting. Returning the bank to the private sector at a time when it could be providing the funds for businesses to grow, and provide the machinery and technology essential to raise productivity, is simply economic "incompetence". Hopes that the electorate will have forgotten such generosity with their assets by 2020 appear to take precedence!
Furthermore, a state-owned RBS could set an example in management to the other high street banks; that would mean some immediate sackings, both of all those employed in the investment arm of RBS culpable for the foreign exchange rigging, the illegal selling of mortgage-backed securities in the US, and all the other scams, and of those at the top responsible for the profit-at-all costs culture, and the obscenely high bonuses. It would also mean absolute compliance with all taxation laws, ensuring the Treasury received its fair share, to be invested in infrastructure, health and education. A bank like this could even attract employees willing to put the needs of the customer first, rather than personal enrichment, and millions of customers preferring to see the huge profits amassed by their bank benefiting the nation as a whole, not just its already rich shareholders.