What: bluebird bio (NASDAQ:BLUE) was up more than 10% Tuesday after rising almost that much on Monday.

So what: There hasn't been any news about bluebird bio this week. The company hasn't issued a press release in almost a month.

It appears investors are buying up shares of bluebird bio ahead of the American Society of Hematology (ASH) meeting. The actual meeting doesn't start until next month, but abstracts are set to be released on Thursday at 9:00 a.m. EST.

bluebird bio has three ongoing clinical trials that management has said will have data released this year. ASH would obviously be the perfect opportunity, but we won't know until abstracts are published.

Investors should keep in mind that the cutoff date for abstract submission was Aug. 4, so the data in the abstract won't be up to date. You'll have to wait for the actual meeting for the latest data.

It's also possible that the abstract for one or more of bluebird bio's presentations won't be released on Thursday because ASH abstracts are released in two batches. Another set that were submitted later as "late-breaking abstracts" will be made available on Nov. 16.

Now what: A run-up in price in anticipation of an event is usually not the best place to be buying in. The increased price is simply an issue of supply and demand, but the company isn't actually worth more. By buying at the end of the run-up, you're missing some of the pop and taking on more risk if the data doesn't turn out like investors are hoping.

But in bluebird bio's case, shares are so far off the high it set after the last data release at the Annual Congress of the European Hematology Association in June that we could still see a nice run if the ASH data is positive.

BLUE data by YCHARTS

As you can see from the chart, last year there was a pop after data was presented at ASH, so investors may have plenty of time to get in.

Brian Orelli has no position in any stocks mentioned. The Motley Fool recommends Bluebird Bio. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.