Should you buy an annuity in tranches?

Most people build an investment portfolio gradually over many decades, through monthly contributions they barely notice. An annuity works the other way. It is bought in one transaction and cannot be undone, often leaving buyers agonising over timing. With annuity rates at an 18-year high, is now the moment, or is it worth waiting for better gilt yields?When you buy an annuity can make a big difference. On Canada Life's benchmark, a healthy 65-year-old with £100,000 bought £4,521 a ye