The big question being debated by banking analysts right now is what impact the "yield trade" will have on bank stocks this year. The major banks' share prices rose by around 20 per cent last year, the biggest re-rating of Australian bank shares since 2001, and investors are keen to know if they can expect more of the same this year.Citi Research published a report earlier this month, which said: "With interest rates remaining low in 2013 and earnings expectation relatively stable, bank share prices will continue to be well supported."Citi's view is that with the Australian government 10-year bond yield hovering around 3.4 per cent, prospective bank dividend yields (based on estimated 2012/13 earnings) offer an attractive spread.Citi has ANZ trading on a prospective yield of six per cent, Commonwealth Bank on 5.5 per cent, NAB on seven per cent and Westpac on 6.5 per cent. All pay fully-franked dividends.The Citi report said: "Bank share prices are a function of the bond yield and the bank yield spread over bonds.Macquarie Securities is not so sure. In an Australian bank review published on January 11, it said: "The banks' safe-haven status is less certain this year, with clear de-rating implications for share prices."There is no doubt that the big four have benefited from the yield trade in 2012. This has been helped by declining domestic rates, as well as the perception that the banks have a pseudo-government risk profile. "However, low interest rates will bring earnings risk into focus. Lower cash rates will increase pressure on net interest margins, rising impairments and low deposit growth.""This is a world of low rates, a painfully high Australian dollar, shrinking domestic demand due to lower government spending and the removal of mining investment. This will challenge the majors in 2013.""Given the strong run the sector has had, we'd expect that as the risks begin to be revealed valuations will come under pressure."Declining assets growth, primarily in the retail banks, has led Macquarie Securities to downgrade its 2013 earnings forecasts for Commonwealth Bank, National Australia Bank and Westpac. It rates ANZ Outperform, CBA Neutral, NAB Neutral and Westpac Underperform.Citi rates CBA, ANZ and Westpac as Buys. It has a Neutral recommendation on NAB.Citi said it did not see much risk of significant deterioration in operating conditions, which would see bank share prices underperform. "Neither corporate nor household credit costs appear likely to threaten bank earnings or dividend reliability."