Russ Koesterich, BlackRock's recently installed global chief investment strategist, has built his outlook for 2013 around assumptions of continued slow economic growth as well as low interest rates and inflation. His views help set the tone for deployment of BlackRock's $3.673 trillion in assets under management, the most of any asset manager. Koesterich, 45, talked shop with IBD from his San Francisco office. IBD: What's your 2013 outlook?