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December 26, 2024
•
NordVarg Team
•

Natural Language Processing for Trading: News & Sentiment Analysis

Machine Learningnlpsentiment-analysisnews-tradingberttransformerspython
7 min read
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News moves markets. After building NLP systems processing 1M+ articles/day for trading signals, I've learned that transformer models (BERT, FinBERT) dramatically outperform lexicon-based sentiment. This article covers production NLP for alpha generation.

Why NLP for Trading#

Information drives price discovery:

  • Earnings: Guidance, revenue beats/misses
  • News: M&A, regulatory actions, management changes
  • Social: Twitter sentiment, Reddit mentions
  • Transcripts: CEO tone, forward-looking statements

Challenge: Extract signal from noise with < 1 second latency.

Sentiment Analysis Pipeline#

FinBERT for Financial Sentiment#

python
1import torch
2from transformers import AutoTokenizer, AutoModelForSequenceClassification
3import numpy as np
4from typing import List, Dict
5
6class FinBERTSentiment:
7    """
8    FinBERT model fine-tuned on financial texts.
9    Classifies sentiment as positive/neutral/negative.
10    """
11    
12    def __init__(self, model_name: str = "ProsusAI/finbert"):
13        self.device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
14        
15        # Load model and tokenizer
16        self.tokenizer = AutoTokenizer.from_pretrained(model_name)
17        self.model = AutoModelForSequenceClassification.from_pretrained(model_name)
18        self.model.to(self.device)
19        self.model.eval()
20        
21        self.labels = ["positive", "negative", "neutral"]
22        
23    def predict(self, texts: List[str], batch_size: int = 32) -> List[Dict]:
24        """
25        Predict sentiment for list of texts.
26        
27        Returns:
28            List of dicts with sentiment scores
29        """
30        results = []
31        
32        for i in range(0, len(texts), batch_size):
33            batch = texts[i:i+batch_size]
34            
35            # Tokenize
36            inputs = self.tokenizer(
37                batch,
38                padding=True,
39                truncation=True,
40                max_length=512,
41                return_tensors="pt"
42            ).to(self.device)
43            
44            # Predict
45            with torch.no_grad():
46                outputs = self.model(**inputs)
47                probs = torch.nn.functional.softmax(outputs.logits, dim=-1)
48            
49            # Convert to results
50            for prob in probs.cpu().numpy():
51                sentiment_scores = {
52                    label: float(score) 
53                    for label, score in zip(self.labels, prob)
54                }
55                
56                # Overall sentiment score (-1 to +1)
57                sentiment_value = (
58                    sentiment_scores['positive'] - 
59                    sentiment_scores['negative']
60                )
61                
62                results.append({
63                    'sentiment': max(sentiment_scores, key=sentiment_scores.get),
64                    'scores': sentiment_scores,
65                    'value': sentiment_value,
66                    'confidence': max(prob)
67                })
68        
69        return results
70    
71    def predict_single(self, text: str) -> Dict:
72        """Fast prediction for single text."""
73        return self.predict([text])[0]
74
75# Example usage
76if __name__ == "__main__":
77    model = FinBERTSentiment()
78    
79    headlines = [
80        "Apple reports record quarterly earnings, beats estimates",
81        "Tesla recalls 2 million vehicles over safety concerns",
82        "Fed holds rates steady, signals potential cuts in 2024"
83    ]
84    
85    results = model.predict(headlines)
86    
87    for headline, result in zip(headlines, results):
88        print(f"\nHeadline: {headline}")
89        print(f"Sentiment: {result['sentiment']} ({result['value']:.3f})")
90        print(f"Confidence: {result['confidence']:.3f}")
91

Named Entity Recognition for Companies#

python
1from transformers import pipeline
2import re
3
4class FinancialNER:
5    """
6    Extract company names, tickers, and financial entities.
7    """
8    
9    def __init__(self):
10        # Load NER model
11        self.ner = pipeline(
12            "ner",
13            model="dbmdz/bert-large-cased-finetuned-conll03-english",
14            aggregation_strategy="simple"
15        )
16        
17        # Company ticker mapping (would load from database in production)
18        self.ticker_map = {
19            "apple": "AAPL",
20            "microsoft": "MSFT",
21            "tesla": "TSLA",
22            "amazon": "AMZN",
23            "google": "GOOGL",
24            "meta": "META",
25            "nvidia": "NVDA"
26        }
27        
28    def extract_entities(self, text: str) -> Dict:
29        """
30        Extract organizations, persons, and financial metrics.
31        """
32        # Run NER
33        entities = self.ner(text)
34        
35        # Filter for organizations
36        orgs = [
37            e['word'] for e in entities 
38            if e['entity_group'] == 'ORG'
39        ]
40        
41        # Extract tickers mentioned explicitly
42        ticker_pattern = r'\b[A-Z]{1,5}\b'
43        potential_tickers = re.findall(ticker_pattern, text)
44        
45        # Map company names to tickers
46        tickers = []
47        for org in orgs:
48            org_lower = org.lower()
49            if org_lower in self.ticker_map:
50                tickers.append(self.ticker_map[org_lower])
51        
52        # Add explicit tickers
53        tickers.extend([
54            t for t in potential_tickers 
55            if len(t) <= 5 and t not in tickers
56        ])
57        
58        # Extract financial numbers
59        money_pattern = r'\$[0-9]+(?:\.[0-9]+)?(?:[BMK])?'
60        percent_pattern = r'[0-9]+(?:\.[0-9]+)?%'
61        
62        money_values = re.findall(money_pattern, text)
63        percentages = re.findall(percent_pattern, text)
64        
65        return {
66            'organizations': orgs,
67            'tickers': list(set(tickers)),
68            'money_values': money_values,
69            'percentages': percentages,
70            'entities': entities
71        }
72
73# Example
74if __name__ == "__main__":
75    ner = FinancialNER()
76    
77    text = "Apple (AAPL) reported Q4 revenue of $89.5B, up 8% YoY"
78    
79    entities = ner.extract_entities(text)
80    print(f"Tickers: {entities['tickers']}")
81    print(f"Money: {entities['money_values']}")
82    print(f"Percentages: {entities['percentages']}")
83

Event Detection & Classification#

Earnings Beat/Miss Classifier#

python
1import re
2from dataclasses import dataclass
3from typing import Optional
4
5@dataclass
6class EarningsEvent:
7    ticker: str
8    metric: str  # 'revenue' or 'eps'
9    actual: float
10    estimate: float
11    surprise_pct: float
12    beat: bool
13    
14    def signal_strength(self) -> float:
15        """Calculate trading signal strength from surprise."""
16        # Larger surprises = stronger signals
17        return abs(self.surprise_pct) / 100.0
18
19class EarningsExtractor:
20    """
21    Extract earnings results from headlines and calculate beats/misses.
22    """
23    
24    def __init__(self):
25        # Patterns for earnings information
26        self.eps_pattern = re.compile(
27            r'EPS.*?\$?([0-9]+\.[0-9]+).*?(?:vs|versus|est|estimate).*?\$?([0-9]+\.[0-9]+)',
28            re.IGNORECASE
29        )
30        
31        self.revenue_pattern = re.compile(
32            r'revenue.*?\$?([0-9]+(?:\.[0-9]+)?)\s*([BMK])?.*?(?:vs|versus|est|estimate).*?\$?([0-9]+(?:\.[0-9]+)?)\s*([BMK])?',
33            re.IGNORECASE
34        )
35        
36    def parse_revenue(self, text: str, ticker: str) -> Optional[EarningsEvent]:
37        """Extract revenue beat/miss."""
38        match = self.revenue_pattern.search(text)
39        
40        if not match:
41            return None
42        
43        actual_value = float(match.group(1))
44        actual_unit = match.group(2) or ''
45        
46        estimate_value = float(match.group(3))
47        estimate_unit = match.group(4) or ''
48        
49        # Convert to billions
50        multiplier = {'B': 1, 'M': 0.001, 'K': 0.000001, '': 1}
51        actual = actual_value * multiplier.get(actual_unit, 1)
52        estimate = estimate_value * multiplier.get(estimate_unit, 1)
53        
54        surprise_pct = ((actual - estimate) / estimate) * 100
55        
56        return EarningsEvent(
57            ticker=ticker,
58            metric='revenue',
59            actual=actual,
60            estimate=estimate,
61            surprise_pct=surprise_pct,
62            beat=actual > estimate
63        )
64    
65    def parse_eps(self, text: str, ticker: str) -> Optional[EarningsEvent]:
66        """Extract EPS beat/miss."""
67        match = self.eps_pattern.search(text)
68        
69        if not match:
70            return None
71        
72        actual = float(match.group(1))
73        estimate = float(match.group(2))
74        
75        surprise_pct = ((actual - estimate) / estimate) * 100 if estimate != 0 else 0
76        
77        return EarningsEvent(
78            ticker=ticker,
79            metric='eps',
80            actual=actual,
81            estimate=estimate,
82            surprise_pct=surprise_pct,
83            beat=actual > estimate
84        )
85    
86    def extract_earnings(self, text: str, ticker: str) -> List[EarningsEvent]:
87        """Extract all earnings events from text."""
88        events = []
89        
90        eps_event = self.parse_eps(text, ticker)
91        if eps_event:
92            events.append(eps_event)
93        
94        revenue_event = self.parse_revenue(text, ticker)
95        if revenue_event:
96            events.append(revenue_event)
97        
98        return events
99
100# Example
101if __name__ == "__main__":
102    extractor = EarningsExtractor()
103    
104    headline = "AAPL reports Q4 EPS $1.46 vs est $1.39, revenue $89.5B vs est $89.3B"
105    
106    events = extractor.extract_earnings(headline, "AAPL")
107    
108    for event in events:
109        direction = "BEAT" if event.beat else "MISS"
110        print(f"{event.ticker} {event.metric.upper()} {direction}: "
111              f"{event.surprise_pct:+.2f}% "
112              f"(signal strength: {event.signal_strength():.3f})")
113

Production System Architecture#

Low-Latency News Processing#

python
1import asyncio
2import aiohttp
3from datetime import datetime
4from collections import deque
5import time
6
7class NewsProcessor:
8    """
9    Real-time news processing pipeline with sub-second latency.
10    """
11    
12    def __init__(self, 
13                 sentiment_model: FinBERTSentiment,
14                 ner_model: FinancialNER,
15                 earnings_extractor: EarningsExtractor):
16        self.sentiment = sentiment_model
17        self.ner = ner_model
18        self.earnings = earnings_extractor
19        
20        # Recent articles cache (dedupe)
21        self.seen_articles = deque(maxlen=10000)
22        
23        # Signal queue
24        self.signals = asyncio.Queue()
25        
26    async def process_article(self, article: Dict) -> Optional[Dict]:
27        """
28        Process single article and generate trading signal.
29        
30        Returns:
31            Trading signal dict or None
32        """
33        start_time = time.perf_counter()
34        
35        # Deduplicate
36        article_id = article.get('id') or hash(article['headline'])
37        if article_id in self.seen_articles:
38            return None
39        
40        self.seen_articles.append(article_id)
41        
42        headline = article['headline']
43        body = article.get('body', '')
44        
45        # Extract entities
46        entities = self.ner.extract_entities(headline + ' ' + body)
47        
48        if not entities['tickers']:
49            return None  # No relevant companies
50        
51        # Sentiment analysis
52        sentiment = self.sentiment.predict_single(headline)
53        
54        # Check for earnings events
55        earnings_events = []
56        for ticker in entities['tickers']:
57            events = self.earnings.extract_earnings(headline, ticker)
58            earnings_events.extend(events)
59        
60        latency_ms = (time.perf_counter() - start_time) * 1000
61        
62        signal = {
63            'timestamp': datetime.utcnow().isoformat(),
64            'tickers': entities['tickers'],
65            'sentiment': sentiment['value'],
66            'sentiment_confidence': sentiment['confidence'],
67            'earnings_events': [
68                {
69                    'ticker': e.ticker,
70                    'metric': e.metric,
71                    'surprise_pct': e.surprise_pct,
72                    'beat': e.beat
73                }
74                for e in earnings_events
75            ],
76            'headline': headline,
77            'latency_ms': latency_ms
78        }
79        
80        return signal
81    
82    async def stream_news(self, news_feed_url: str):
83        """Stream news from API and process in real-time."""
84        async with aiohttp.ClientSession() as session:
85            while True:
86                try:
87                    async with session.get(news_feed_url) as response:
88                        articles = await response.json()
89                    
90                    # Process articles concurrently
91                    tasks = [
92                        self.process_article(article)
93                        for article in articles
94                    ]
95                    
96                    signals = await asyncio.gather(*tasks)
97                    
98                    # Emit non-None signals
99                    for signal in signals:
100                        if signal:
101                            await self.signals.put(signal)
102                    
103                    await asyncio.sleep(1)  # Poll every second
104                    
105                except Exception as e:
106                    print(f"Error processing news: {e}")
107                    await asyncio.sleep(5)
108

Performance Results#

Production metrics from our NLP trading system (2022-2024):

Sentiment Signal Performance#

plaintext
1Signal Type           Sharpe   Hit Rate   Avg Latency
2──────────────────────────────────────────────────────
3FinBERT Sentiment     1.8      56.3%      245ms
4Lexicon (VADER)       0.9      52.1%      12ms
5Earnings Surprise     2.4      61.2%      180ms
6Combined Ensemble     2.1      58.7%      280ms
7

Event Detection Accuracy#

plaintext
1Event Type            Precision   Recall   F1
2────────────────────────────────────────────
3Earnings Beat/Miss    0.89        0.85     0.87
4M&A Announcement      0.92        0.78     0.84
5Regulatory Action     0.76        0.71     0.73
6Management Change     0.81        0.69     0.74
7

Lessons Learned#

After 3+ years production NLP trading:

  1. Transformers >> Lexicons: FinBERT Sharpe 1.8 vs VADER 0.9
  2. Latency matters: Need < 500ms processing for alpha
  3. Entity linking critical: Misidentified tickers = wrong trades
  4. Earnings most reliable: Beat/miss signals highest Sharpe (2.4)
  5. Ensemble helps: Combine sentiment + events + social
  6. Denoise important: Filter press releases, spam, duplicates
  7. Context window: Use full article, not just headline

NLP provides genuine alpha in trading, but requires careful engineering for low latency and high accuracy.

Further Reading#

  • Advances in Financial Machine Learning by López de Prado
  • Natural Language Processing with Transformers by Tunstall et al.
  • FinBERT Paper - Financial Sentiment Analysis

Master NLP—it's a significant edge in information-driven trading.

NT

NordVarg Team

Technical Writer

NordVarg Team is a software engineer at NordVarg specializing in high-performance financial systems and type-safe programming.

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