It’s been another busy week so far in the biotech space, with a number of companies logging sharp gains and losses on various developments. Here are two of the biggest movers, one big one small, and a look at what’s driving the action in both.

Let’s start with the large side of the market. At market close on June 13, Perrigo Company plc Ordinary Shares (NYSE:PRGO) went for a little less than $100 a share. The company has had a bit of a wild ride this year, primarily on the back of its CEO leaving to join the embattled Valeant. When the rumors that this leaving hit press, markets sold off on Perrigo to the tune of 23%, and the company has done little to make back this lost ground since then. That is, until now. At market close on June 14, Perrigo shares went for a little over $108 – a close to 10% premium on the week’s open.

So why the gains? Well, there is a rumor going around that Perrigo is fielding a takeover bid somewhere in the region of $20 billion. Exactly where this bid came from we don’t know – indeed, whether it even exists remains unknown – but it’s reportedly from a UK company.

This isn’t the first time Perrigo has been subject to buyout rumors, and on the one occasion last year that these rumors hit press, they turned out to be substantiated. No deal went through in the end, but Mylan NV (NASDAQ:MYL) made an aggressive attempt to force an acquisition. The price back then was a $26 billion offer, so if the rumors are to be believed, the UK company in question is going in low. With this in mind, and based on the fact that shareholders were responsible for the unsuccessful completion of the Mylan deal, chances are a $20 billion offer is not going to get very far.

It’s done enough to excite markets, however, and therein lies the driver behind the week to date gains. We’ll keep an eye on things as they progress, and update accordingly. If last year’s debacle is anything to go by, it could be 7-10 months before we see any deal concluded, successfully or otherwise, but it’s one to watch going forward nonetheless.

Moving now to the lower end of the market, let’s take a look at Achaogen Inc (NASDAQ:AKAO). Achaogen kicked off the Wednesday session in the US a little over *8% higher than its Tuesday close, before spiking to a close to 25% premium. As things stand, this premium has dropped back down to circa 9%. Why the upside? This one is rooted in an upcoming data presentation regarding the company’s lead development candidate, and an upgrade (likely in anticipation of this data presentation) from Wedbush. The company is developing a drug called plazomicin, with which it is targeting a host of multi drug resistant (MDR) bacteria. Specifically, it’s using the drug to go after a family of MDR bacteria called Enterobacteriaceae, which includes some pretty well known (and pretty serious) targets – Salmonella, e-coli and Shigella to name just three of many. At the American Society for Microbiology (ASM) Microbe 2016 Annual Meeting, which is scheduled to kick off tomorrow morning (June 16) in Boston, Achaogen will present on six separate abstracts, each relating to the impact of its lead development candidate on certain enzymes and bacteria that fall under the umbrella of its MDR target category.

The assumption with these sorts of presentations is that no company would volunteer to address a crowd of biotech professionals with anything other than promising data, and in turn, that the data Achaogen is set to report is indicative of efficacy across its target samples. As mentioned, Wedbush upgraded the company (from neutral to outperform, as of June 14) and this upgrade is likely based on the aforementioned assumption.

So what do we expect going forward? Well, chances are we will see a round up of the presented data post release, and this will offer insight into the drug’s (and in turn, the company’s) potential. As such, we are looking to this roundup as a near term upside catalyst. Beyond that, plazomicin clinical efficacy data becomes the focal point.