NEW YORK (TheStreet) -- Investors are betting on which company will be the next Idenix  (IDIX) -- a hot target for a buyout. The favorites on Achillion Pharmaceuticals  (ACHN) and Inovio  (INO - Get Report).

Drug giant Merck  (MRK - Get Report) announced Monday that it would acquire Idenix for $3.85 billion. The company's "promising portfolio" of hepatitis C treatments was the main driver of the deal, according to Merck's Research Laboratories president.

Many investors speculate that the $24.50 per share cash deal -- a more than 233% premium over the prior closing price -- was so high because of a bidding war with Merck competitors. And they believe the losing bidders -- reportedly Johnson & Johnson  (JNJ - Get Report) and Abbvie  (ABBV - Get Report) -- could now try to secure Idenix competitors with promising hep C drugs of their own.

$MRK need not have paid 4x the share price for $IDIX...Bidding war is absolutely active behind the scenes. $ACHN and $IDIX pretty similar.

? Golden Gate Sings (@goldengatesings2) Jun. 10 at 12:12 PM

$ACHN Abbvie and J&J are currently completely locked out of the Hep C market....ACHN will get its premium is my bet.

? Golden Gate Sings (@goldengatesings2) Jun. 10 at 12:11 PM

Achillion Pharmaceuticals has several Hepatitis C treatments in human trials. The company announced today that it began dosing patients with chronic hepatitis C with its ACH-3422 drug and will report the results in the fall. It also announced that the FDA removed a clinical hold on sovaprevir, another hepatitis C treatment. Sovaprevir is in Phase 2 clinical trials and can resume dosing patients with hepatitis C. The company can also dose some healthy control patients, but not as many times, according to the FDA.

The stock surged more than 53% after the news.

All the A named bios came back from FDA adversity $ARIA $ACHN next is $AFFY if drug comes back upside over 1,000%

? So Generous (@sogenerous) Jun. 10 at 12:12 PM

Inovio Pharmaceuticals also has several hepatitis vaccines, also known as immunotherapies. It has a hepatitis C vaccine in Phase 1 human trials and a hepatitis B vaccine in preclinical trials. The company's pipeline also includes vaccines for HIV, influenza, malaria and HPV strains that cause cervical cancer and head and neck cancers.

Traders betting on Inovio to be next Idenix? $INO (also has hep C treatment) up 5% & top trender on StockTwits. $IDIX up 233% on $MRK deal??

? John L. Bair (@JohnLBair1) Jun. 9 at 11:38 AM

Some investors say the buyout hype is overdone. Just because multiple companies were interested in Idenix, they argue, doesn't mean they will purchase less attractive competitors -- especially after their stocks have run up on acquisition hopes.

@JoeyBagadonuts Going long much on nothing concrete to drive it up besides....rumors ? All rumors usually end up in the same place. DOWN

? TraderX82 (@TraderX82) Jun. 10 at 12:09 PM

But many think an acquisition is in the offing for the two companies. Sentiment is 97% bullish on Inovio and 90% bullish on Achillion, according to StockTwits' analytics.

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At the time of publication, the author held no positions in any of the stocks mentioned.

This article represents the opinion of a contributor and not necessarily that of TheStreet or its editorial staff.