New York State Teachers' Retirement System, Albany, has lost nearly $12 million on its holdings of Delta Air Lines. The $77 billion pension fund owns 450,000 shares of the Atlanta airline. The stock, worth about $13.2 million, or $29.45 per share when the fund originally bought it, was trading around $3.35 per share at midday today. Delta executives for the past several weeks have said the company could be close to filing for Chapter 11 bankruptcy protection. John Cordillo, a spokesman for the New York fund, declined to comment, citing the system's policy of not commenting on specific holdings.