Every auction is either open — bidders see what others are doing and respond — or sealed, where each party submits once, blind, and the bids are opened together. The choice between them is not stylistic. It changes what bidders reveal, what price you achieve, and what your process can be challenged on.
Open bidding
Bidders see the current price and can respond. This covers live outcry, timed online auctions and most of what people picture when they hear the word auction.
Why it usually produces more: competition is visible and it escalates. A bidder who would have stopped at $400 goes to $450 because someone else went to $425. That responsiveness is the whole engine of price discovery, and it is why open formats dominate wherever maximising price is the goal.
What it requires: real-time bid distribution, proper serialisation under concurrency, and soft-close extension so late bids do not simply end the competition. See proxy bidding and bid increments.
Where it fails: thin markets, where visible lack of competition tells bidders they can stop early. And any process where revealing bid amounts publicly is inappropriate.
Sealed bidding
Each bidder submits once, without seeing anyone else’s bid. All bids open at a published time and the highest — or best-scored — wins.
Why it exists: fairness and defensibility. Nobody can respond to anyone else, which means nobody can be advantaged by timing, connection speed or information. In public procurement and property disposal this matters more than squeezing the last few percent.
The strategic effect on bidders: without the ability to observe and respond, bidders must submit their genuine maximum — or something close to it — first time. That can produce strong single bids. It can equally produce conservative ones from bidders hedging against overpaying.
What it requires from software: genuine encryption at rest so that no one, including administrators, can view bids before opening; a published opening time; simultaneous reveal with the opening event itself logged; and a complete audit trail. If an administrator can see sealed bids early, you do not have a sealed bid process — you have a liability.
Variants worth knowing
- First-price sealed bid. Highest bidder wins and pays their bid. Standard in procurement and property disposal.
- Second-price (Vickrey). Highest bidder wins but pays the second-highest bid. In theory this makes bidding your true value the safe strategy. Rare in practice because it is hard to explain and requires bidders to trust that you reported the second price honestly.
- Sealed bid with best-and-final. An initial sealed round shortlists, then shortlisted bidders submit one final sealed bid. Common in commercial property and complex procurement — it captures some competitive pressure while keeping the process defensible.
- Multi-parameter sealed bid. Bids scored on price plus quality, delivery and service against published weights. The correct format for anything where lowest price is not the same as best value. See what a reverse auction is.
Choosing between them
Use open bidding when:
- Maximising price is the primary goal
- You have genuine competition — several credible bidders
- The item’s value is uncertain and you want the market to discover it
- Transparency of the process is not a regulatory requirement
Use sealed bidding when:
- Regulation or policy requires it, as in most public procurement
- The process must be demonstrably fair and challenge-resistant
- You are evaluating on more than price
- Bidders would be disadvantaged by differences in connection or availability
- Revealing bid amounts publicly would be commercially inappropriate
The hybrid that works well
A pattern worth knowing: a sealed round to establish serious interest and shortlist, followed by an open competitive round among the shortlisted bidders.
You get the defensibility of sealed submission at the qualification stage and the price escalation of open bidding at the decision stage. Commercial property and complex sourcing both use this regularly, and it is generally the best of both where the rules permit it.
What both formats need
Regardless of which you choose: bidder qualification before participation, an immutable audit trail, clearly published rules that you then follow exactly, and results published as recorded. The most common cause of a challenged auction is not the format — it is a process that deviated from its own stated rules.
Related: absolute vs. reserve auctions, what a Dutch auction is, and forward vs. reverse auctions.
Frequently asked questions
Which format gets a higher price?
Open bidding, generally, because visible competition escalates. Sealed bidding trades some price for fairness and defensibility.
Can sealed bids be manipulated?
Only if the system allows early viewing. Proper encryption at rest, a published opening time and a complete audit trail are what prevent it — and what let you prove it did not happen.
Do I need both formats?
If you sell across contexts — routine disposals and formal procurement, say — yes. Talk to our team about supporting both in one platform.
