Upload & Sell: Off
No, I am not concerned. Japanese stocks were down as a whole; currently, Nikon stock is up over 1%. What was the stock trading acumen and experience of the people whose "Tweets" you read? Do you know them to be knowledgable about such matters? If so, then perhaps concern is warranted; at this point, and as a stock owner who has seen many ups and downs in my portfolio, I prefer to worry about something else!