MM's do not sit next to eachother on a trading day. Market Makers ALWAYS look after one another. They are the ones creating the flow, the market, the price for that particular stock (especially a pink or OTC). So in order to "signal" something, they don't send telegrams, they don't send emails (time consuming... I think), and they don't call eachother on the phone. They do it by putting in tiniest orders for eachother to understand where they want the stock price to go.
Like if me & you were MM's. I'd sell 50 shares of a stock to see you I want to drop the price a little more. 100 shares means A lot more.
I truely believe that happens in pink land.
News 
Market Data 
Discover 
