Is because Yahoo hasn't yet activated the "message board" link on the main page for AMBA. The only way to get here is through another message board, and people don't typically know to do that. But you can be sure there are a lot of eyes on this stock.
Yes, there is a way. The problem is that this company recently did their IPO, so it takes a while for Yahoo to activate all the links for new stock tickers. But this is taking much longer than usual. So if enough investors care to take the following steps, the problem can be resolved quickly.
"When a ticker symbol is changed or switches exchanges, there can be up to a two week delay before that symbol's Message Board becomes active on Yahoo! Finance. If this amount of time has already elapsed, and a symbol's Message Board is still missing, you may notify Yahoo! staff:"
1.Click Help at the top of any Yahoo! Finance page.
2.On the right, select "Make a suggestion" and follow the on-screen instructions.