The S&P/ASX 200 Index (ASX: XJO) is back on from and pushing higher on Thursday afternoon. At the time of writing, the benchmark index is up 0.3% to 8,487.9 points.

Four ASX shares that have failed to follow the market higher today are listed below. Here's why they are falling:

29Metals Ltd (ASX: 29M)

The 29Metals share price is down 28% to 26.5 cents. This has been driven by the completion of the institutional component of the copper miner's equity raising this morning. 29Metals has raised approximately $154 million at 27 cents per share, which represents a 27% discount to its last close price. The copper miner will now push ahead with the retail component of the equity raising, which aims to raise approximately $26 million on the same terms. The proceeds will support a balance sheet reset and fully fund the Gossan Valley project to first ore. The latter was approved by the company's board earlier this week.

Guzman Y Gomez Ltd (ASX: GYG)

The Guzman Y Gomez share price is down 4% to $43.08. This may have been caused by comments out of Bell Potter's Richard Coppleson yesterday. As we covered here, he believes the Mexican fast food chain's shares are vastly overvalued at current levels and destined to crash deep into the red. He said: "Now as soon as this buying has been exhausted – given the view of the stock from all the brokers, the excessive rally and the astronomical – sky high – PE (in fact I've very rarely seen one that high) – there is a very high chance that this suffers a big selloff (PE de-rating) in December."

Mesoblast Ltd (ASX: MSB)

The Mesoblast share price is down 8% to $1.62. This morning the biotechnology company revealed that the United States Food and Drug Administration (FDA) has granted its second generation allogeneic, STRO3-immunoselected, and industrially manufactured stromal cell therapy Revascor Regenerative Medicine Advanced Therapy (RMAT) designation. This should be classed as very positive news. In light of this, it seems that today's decline is a classic 'buy the rumour, sell the news' situation.

Pilbara Minerals Ltd (ASX: PLS)

The Pilbara Minerals share price down over 1.5% to $2.36. This is despite the lithium miner's proposed acquisition of Latin Resources Ltd (ASX: LRS) getting a boost today. This morning, the Brazilian National Mining Agency approved the Integrated Plan of Economic Development. This approval satisfies the condition precedent in the two parties' scheme implementation agreement. Shareholder and court approval is still required. Concerns that lithium prices may stay lower for longer appears to have offset this positive development.