HIV fighter Biotron took investors on a wild rollercoaster ride Tuesday — soaring 70 per cent to 44.5c before plummeting back to 24.5c to close down 6 per cent.

Some $50 million worth of shares changed hands today — though trade was very volatile and the stock rose and fell sharply.

Three weeks ago the biotech (ASX:BIT) was valued at $9 million. Yesterday it flew past a $100 million valuation — closing up 53 per cent for a market cap of $130 million. By 10.45am AEST today it was worth more than $160 million before falling back.

The shares hit a record high of 44.5c just before 10.30am AEST — up more than 2000 per cent since closing at 1.9c on September 27.

But an hour later they had dropped back to around 27c amid heavy trading (see graph below). They fell all the way to 21.5c as investors rushed for the exit, before recovering slightly to close at 24.5c.

The Sydney-based small cap has experienced one of the year’s most extraordinary runs after two weeks ago announcing positive trial results for its HIV treatment.

On Monday Biotron told investors it had received a $1 million R&D tax refund — though managing director Dr Michele Miller reiterated that the current trial was already fully funded.

Biotron earlier confirmed to Stockhead it was on the hunt for a funding partner to move to the next stage of testing.

Here’s a look at the stock over the past week:

What goes up ... Biotron's crazy week (ASX:BIT)
What goes up … Biotron’s crazy week (ASX:BIT)

Investors on stock trading forum Hot Copper had earlier been speculating about a $1 share price. Here are a few comments before the plunge back to earth:

— “No oxygen up here, gimme the mask…….Eagle1 to ground control….”

— “I have never seen anything like it. Must be something really big going on here. And look at that volume!! I’m impressed”

— Out at 41c back in at 33.5c – priceless!

— “It’s been a long while since I have seen a stock with such relentless bullish momentum like this has had ALL day … well done to the long-time holders.”

— “It’s steroids are on steroids … not gonna lie, when I saw people predicting 25c close I thought ‘no way’.”

Shortly after the original announcement the stock jumped 750 per cent to 18c before profit-taking saw it halve to 8c.

On Monday more than $15 million worth of shares — or about 3 per cent of the stock — changed hands. Today the value of trades hit $50 million.