NLP is a possibility, but bear in mind that HFT is all about optimization. The confidence levels desired can vary significantly based on what you intend to do with the information.

Acting on M&A news by taking a more aggressive position generally requires more confidence than, say, backing off based on ‘bad’ news. In the first case, you want to be pretty sure of the headline before taking action. In the latter, the mere presence of words like ‘fraud’ and ‘investigation’ might be enough to play it safe and say, “we’re going to back off trading this underlying until a human has a chance to look at this.”