Stay away from financial stocks like mortgage insurer MGIC ( MTG), Jim Cramer said Thursday on CNBC's Stop Trading! segment. Cramer said the sector is "dreadful" and that investors must resist the temptation to assume the worst is past in the housing sector. Cramer said that until we've seen $500 billion in mortgage defaults, it is simply too dangerous to try buying any of the financial names -- let alone an outfit like MGIC that just cut its dividend by 90%. Cramer also said investors should avoid oil service company Nabors ( NBR), which he likened to Baltic Ave. on the Monopoly board. Cramer said even Schlumberger ( SLB), which was "Park Place" before last Friday's earnings miss, is a dubious investment right now. Cramer also said the market should be down more than it is today, given the horrid top-line performances this quarter by recent earnings reporters Comcast ( CMCSA), LabCorp ( LH) and Zimmer ( ZMH).