"I want to remind all my friends to trade with caution, as this market can cause significant losses."

Or, in a more conversational tone:

"Hey friends! Don't forget to trade wisely and be cautious. Market volatility can lead to huge losses, so let's stay alert and make informed decisions."

Alternatively:

"Reminder to all my friends: Trading requires caution! Market fluctuations can result in substantial losses. Stay vigilant and trade smart!"