Chatter is nice, it's a fun system and its great that we have it. It also tends to come with the negative that it provides answers that could otherwise have been found out through actions and/or RP quite easily against essentially a mechanical check.
It also comes into conflict with Trading skill when it comes to CorpShares, so I would like to propose a split in how this is approached:
1. Introduce a new 'speculate' command useable on CorpShare Tickers. This command checks against Trading and relevant substats and allows you to predict market movements based on the results of your check, with arrows indicators assigned behind each stock, of 1 to 3 up or down arrows compiled as a mixture between strength and duration of the trend of that stock. This bit of information is reliably accessible and its quality is somewhat predictable based on your (or whoever is doing it) skill. This also opens up the door to a whole lot of RP, in terms of friends and associates receiving market tips from those in the know, and indeed an entire profession of brokers and stock managers that can market their skills to others.
2. Introduce Chatter about market movements as planned, but as these are chatter and rumours, make them unreliable as they should be. Whenever you receive CorpShare chatter, it randomly decides of what quality that chatter really is. It could be an unsubstantiated rumor making the rounds based on something someone overheard, or it could be an insider tip worming its way through the right circles. Think of it in a way as you're unsure how good the person originating the chatter is at Trading, and you might hit it big or you might not, it's just chatter after all, and it shouldn't replace the truly skilled.
I think Trading has a bit of a hole in its usefulness to exactly the niche of characters that CorpShares are most relevant to, and this is a way that not only grants the skill usefulness, but grants the skill usefulness -to others-, where it is not merely affecting the personal transactions or experience of the people having Trading.
It lets people pick "their stocks guy" and drives arguments between those with different predictions, or the guy with the hot tip he got from chatter, and overall makes the CorpShare system a more social topic.
