Reporting season has already claimed some scalps, and will see the knife taken to more stocks before it's done. Ben Griffiths highlighted the need to be decisive when a stock has gone against you, with some simple advice: Be a slow buyer, but a fast seller. Here is what he told the audience at Livewire Live:

"Blow-ups, basket cases, implosions, they are occupational hazards of this business. When you're a portfolio manager, you go into battle every morning and you're anxious about the portfolio, 55 names you got. And sometimes, you walk in to some rippers, where they do turn on you. And you've got act quickly. We had two in the last two or three years. Slater and Gordon, and Vocational Training.

It's amazing how you can be on top of a story, in the case of Slater and Gordon, you can be passionate supporters and believers in management, and buy into the roll-up concept, but at some point, you start to challenge what's actually happening there. And then when something goes wrong, really wrong, and there was a major system failure with Slater and Gordon, as many in this room will recall, you need to act. And that was one of our biggest active positions in the portfolio. We thought the underlying fundaments of the business were generally weren't too bad, but something was starting to come horribly, horribly undone within that business. We needed to move.

Larry Williams is a fantastic technical trader that I follow out of the US, and he said:

"As a fund manager, if you get one thing right, as you go through your career, it's learn to be a slow buyer, and a fast seller."

If you can master that, you will be well down the way of being a successful manager of money. And that's not easy to do, because when a stock's moved against you on the downside, it's through your purchase price, and starting to hurt you, you are instinctively wanting to will the stock back up, and hoping I'll buy some more when it gets cheaper, but there comes a time when you have got to act."

You can see the video here: