Six weeks after Vanguard Health Systems completed a disappointing initial public offering, many of the investment banks that steered that deal have come out with 'buy' — or the equivalent 'outperform' or 'overweight' — ratings. That makes sense, since the stock (Ticker: VHS) is down 10 percent even from its haircut IPO level. Among the firms advocating that investors step in now and calling for the stock to rise above $20 are Barclays Capital ($22), Gleacher & Co. ($20), Ticonderoga Securities ($21), Robert W. Baird ($22), Lazard Capital Markets ($21) and JPMorgan ($22). Citigroup is the relative outlier: It has a price target of $19.