Nobody knows what the long term effect will be, but it is likely that mortgage rates will drop to historically low levels. The stock market hates surprises, so the huge sell off yesterday was not unexpected. However, the U.K. is only about 4% of the world economy, and it doesn't leave the EU immediately. So the economic impact is likely to be much less than the market reaction suggests. While the U.K. starts to renegotiate its trade and economic relationships globally, its current ties to Europe and the world remain unchanged. U.S. companies will continue to operate in Britain as before, and British companies will continue to participate globally. It will be interesting to see what happens on Monday when financial markets are again open for business.