Over a year ago, this column made an argument about traditional 60-40 equity bond portfolios, which went along the following lines. Over the previous 30 years, these balanced portfolios had enjoyed great success, reflecting large equity rises and a slow but steady decline in bond yields. The corollary of low and lower bond yields is that bond prices rise, so investors enjoyed steady and sometimes even spectacular returns from both equites and bonds over this period. Even during reasonably good times, the dividends from bond yields provided a decent income stream, such that investors did really well over the longer…