Zephyr Deal Database Construction - Corpus from various resources

Database Overview

This document describes the construction of a merger and acquisition (M&A) deal database extracted from Zephyr (Bureau van Dijk), focusing on deals with target trade descriptions for Natural Language Processing (NLP) analysis.

Source Data Extraction

Zephyr Search Strategy

Data Processing Pipeline

1. Initial Export Challenge

Due to Zephyr's export limitations (maximum rows per export), the data was downloaded in 5 batches:

Batch	Deals Count
Batch 1	11,235
Batch 2	11,235
Batch 3	11,235
Batch 4	11,235
Batch 5	10,358
Total Unique Deals	55,298

2. Why Observation Counts Differ

The raw CSV files contain more observations than unique deals because:

• One deal may have multiple acquirers → appears as multiple rows

• One deal may have multiple targets → appears as multiple rows

• Each unique combination (acquirer-target pair) generates a separate row in the export

• 3. Batch Processing Statistics

Target Overview Corpus

Batch	CSV Observations	After Cleaning & Dedup	After Merge with Dates	Final (Year ≤ 2024)
Batch 1	25,526	~842	9,158	~8,953
Batch 2	20,465	~680	8,823	~8,640
Batch 3	17,803	~580	7,806	~7,611
Batch 4	16,201	~415	5,906	~5,766
Batch 5	14,327	~237	3,846	~3,782
Total	94,322	~2,754	35,539	~34,752

Target Trade Description Corpus

Batch	CSV Observations	After Cleaning Missing Data	After Deduplication	After Merge with Dates	Final (Year ≤ 2024)
Batch 1	25,526	11,235	898	9,371	9,158
Batch 2	20,465	11,235	797	9,581	9,381
Batch 3	17,803	11,235	771	9,603	9,360
Batch 4	16,201	11,235	716	9,489	9,280
Batch 5	14,327	10,358	684	8,871	8,733
Total	94,322	55,298	3,866	46,915	45,912
Note: The trade description corpus retains more deals because this field has fewer missing values compared to target overview text.

Summary Statistics

Metric	Target Overview	Target Trade Description
Total unique deals exported	55,298	55,298
Total CSV rows (raw)	94,322	94,322
After cleaning missing data	55,298	55,298
After deduplication	~2,754	~3,866
After merge with dates	35,539	46,915
Final deals with year ≤ 2024	~34,752	~45,912
Data retention rate (from unique deals)	~62.8%	~83.0%
Average rows per deal (raw)	~1.7	~1.7

Comparison with Target Overview Corpus

Aspect	Target Overview	Target Trade Description
Field name	tar_overview	tar_trade_descr_en
Content type	Company overview/description	Trade/business activity description
Language	Mixed (mostly English)	English only
Final sample size	~34,752	~45,912
Missing data rate	~37.2%	~17.0%
Use case	General company NLP	Trade-focused NLP