There is a good reason why we lack a definitive account of what characterises the end of bull markets, in the sense of a prescriptive set of conditions that must be met for such an outcome to be logically anticipated by investors. Such a set of rules would of course be self-fulfilling (and therefore worthless) if widely known and acted upon. Only with hindsight, when earnings and economic data are revised to accord with reality, do we typically discover for certain what should have told us the end was approaching. What we do know from historical precedent is that bull markets (a) tend to end with a whimper, not a bang and (b) are rarely triggered by specific causes that have been prominently highlighted for months in advance. Given their current dominance of the headlines, it seems unlikely therefore that either a new Greek crisis or a September interest rate rise from the Federal Reserve will be the trigger that abruptly brings the current bull market to an end.