Lloyds may have passed the Europe-wide stress tests, but the UK's own bank-health checks may be an issue, according to broker Jefferies which downgraded the stock from 'hold' to 'underperform' on Monday.The broker said it likes Lloyds and its prospects but the risk/reward balance on the shares is "now skewed to the downside".Results from the European Banking Authority's (EBA) stress tests showed that while 24 of the 130 European banks had failed, all of Britain's high-street lenders had passed.Nevertheless, Jefferies still pointed out that Lloyds "fare[d] worse than expected" with an estimated common-equity tier-one (CET1) capital ratio of 6.2%, compared with the EBA's 5.5% threshold.As such, the broker reckons that Lloyds is now "at risk" ahead of the Prudential Regulation Authority's (PRA) forthcoming stress tests, the results of which are due on 16 December.The PRA's review will encompass the EBA test in addition to UK-specific macro elements, including a 35% fall in house prices and a 30% drop in commercial real estate (CRE) prices. The CET1 threshold is 4.5% in the UK test.Jefferies said: "None of this bodes particularly well for LLOY given that it is UK mortgage centric (60% of first-half customer loans are in secured retail)."The 2014-2016 adverse cumulative loss on LLOY's UK retail secured exposures in the EBA's stress test was 1.26% (based on a 15% fall in UK house prices) which is almost certain to be substantially higher under the PRA's more onerous test."The broker expects Lloyds to "marginally" pass the UK test with a CET1 of 4.8%. However, it will have to run with a higher capital ratio than originally thought "to reflect idiosyncratic risks specific to UK mortgage and CRE exposures".As such, Jefferies said it doesn't expect Lloyds to pay out material dividends until 2016.The broker kept a 69p target price for the stock, which had fallen 2.3% to 74.95p by 10:25.