Procurement Anomalies
Shared Address Collusion Clusters
Clusters vendors sharing physical addresses, phone numbers or bank branches to expose bid rigging.
Why shared identifiers signal collusion
Bid rigging frequently hides behind separate company registrations that nonetheless share a physical address, telephone number or bank branch, and unmasking these clusters is a core forensic technique used by the Competition Commission and the SIU. For the auditor, common identifiers across ostensibly competing bidders undermine the very competition that section 217 of the Constitution requires. AuditPro Core clusters vendors on shared attributes so connected bidders posing as rivals are exposed before an award is made.
The Numbers
AuditPro Core renders this view from your tenant's live, tamper-evident records. The figures below are illustrative sample data.
Address Clusters
46
2+ vendors each
Vendors in Clusters
118
▲ 19
Co-Bidding Tenders
73
competed together
Spend in Clusters
R 88.3m
Clusters by Shared Attribute
Largest Co-Bidding Clusters
| Cluster | Vendors | Co-bid Tenders | Spend (R'000) |
|---|---|---|---|
| CL-07 | 5 | 14 | 22400 |
| CL-12 | 4 | 9 | 16800 |
| CL-19 | 3 | 7 | 11200 |
Figures shown are illustrative sample data for demonstration. AuditPro Core renders these views from your own tenant's live, tamper-evident records.
Cover quoting
In a rigged process, related entities submit deliberately uncompetitive bids so a pre-chosen vendor wins at an inflated price. Shared contact details are a common fingerprint of this arrangement.
Identifiers that link entities
Address, landline, cellphone, email domain and bank branch are all attributes that legitimate competitors rarely share. Overlap across multiple identifiers sharply raises the probability of a connection.
Clusters, not pairs
Collusion often spans three or more entities. Graphing the relationships into clusters reveals rings that a simple two-way duplicate check would miss.
Legitimate overlaps
Shared business parks or banks can be innocent, so clusters are investigative leads, not verdicts. The value is in prioritising which bid sets warrant a closer look.
How AuditPro Core Bridges the Gap
- Entity clustering: groups vendors sharing address, phone, email or bank attributes into linked networks.
- Exception workflow: bid sets containing clustered vendors are flagged for evaluation-committee review before award.
- Traceability to source: each link is evidenced back to the vendor master and bid documents for referral if needed.
- Audit-ready export: produces a collusion-cluster schedule suitable for Competition Commission or SIU referral.
Key Takeaways
- Competing bidders sharing contact or banking details is a classic rigging signal.
- Look for clusters of three or more, not just duplicate pairs.
- Treat clusters as leads requiring investigation, not automatic guilt.
- Resolve flagged bid sets before award to protect competitiveness.
See This on Your Own Data
AuditPro Core renders this dashboard from your tenant's live, tamper-evident records — every figure traceable to source.