A precise transaction of 249.999 BTC is something very unusual.
Well, actually there are also 299.999 and 199.999 transactions there too.
And yep, I'd say the same. Somebody (person, institution, consortium, whatever) is accumulating. And the 0.999 part most probably comes from deducting the withdrawal fee by the exchange.
This might suggest that there will be a surge for BTC and other cryptocurrencies?
Imho this suggests that somebody believes in Bitcoin and invests big bucks in it. Really big bucks...