When sales drop on Mercado Libre, the instinct is to reach for advertising: “raise bids,” “add budget,” “restart campaigns.” But often, the issue lies not in advertising but in inventory, fulfillment, and hidden OOS. Conversely, there are times when the inventory is fine, but the advertising has “overheated” and is eating into the results.
This article is a quick 10-minute test that helps answer the main question:
Is the drop due to inventory/fulfillment or due to advertising?
First, let's agree: what we call a “drop”
A drop is a noticeable deterioration in one or more metrics:
- sales (units) / revenue,
- card conversion rate (CR),
- share of advertising expenses (DRR),
- impressions/positions (if visible).
Important: compare “day to day” or “week to week,” not “today vs average for the month.”
Quick test: 3 questions that separate the causes
Question 1. Is the product actually available for purchase with normal delivery?
Check with your eyes as a buyer:
- can it be purchased?
- what is the delivery time?
- are the stocks “spread out” across warehouses so that delivery has become long?
If delivery has significantly worsened or it cannot be purchased — this is an inventory/stock issue. Even if “there are stocks somewhere,” long delivery = hidden OOS.
→ OOS Protocol: OOS: 24-Hour Plan
Question 2. Has DRR increased or remained stable?
Look at:
- advertising expenses
- revenue
- DRR = expenses / revenue
If DRR has sharply increased, this is a signal:
- advertising has become more expensive,
- or revenue has fallen faster than expenses,
- or advertising is pouring into a void (often due to an inventory issue).
Question 3. Has the conversion rate (CR) for the card dropped?
If CR has dropped, advertising is usually “not to blame” as the primary cause — it simply brings traffic to a card that has stopped selling.
CR often drops due to:
- price and competitors,
- delivery,
- ratings/reviews,
- lack of popular variations,
- inventory issues.
Decision tree (very practical)
Scenario A: Delivery has worsened / SKU is unavailable
Cause: inventory / warehouse / hidden OOS.
What to do:
- turn off advertising for this SKU (to avoid wasting)
- check inventory across warehouses and variations
- restore availability/fulfillment
- gradually return advertising
Scenario B: Delivery is normal, but DRR has increased, and CR has not changed
Cause: advertising (auction/bids/semantics).
What to do:
- clean traffic, cut “junk”
- gradually lower bids
- separate exact queries from broad ones
- redistribute budget to better SKUs
→ more details: How to Lower Bids Without Dropping Sales and DRR Increased: Causes and What to Do
Scenario C: Delivery is normal, DRR has increased, and CR has dropped
Most often, the primary cause is the card/offer (or price/reviews), with advertising being secondary.
What to do:
- first fix CR (cover, price, delivery, reviews)
- then optimize advertising
→ useful: Advertising Exists, Profit is Falling
Scenario D: Delivery has worsened and DRR has increased
Almost always, inventory/stock is the primary cause. Advertising has simply exacerbated the pain by buying clicks on a product that is poorly available.
What to do:
- urgently follow the OOS plan
- turn off/cut advertising
- restock/redistribute
- restore traffic
Scenario E: DRR has not increased, but sales have dropped
Then it is likely:
- seasonality / demand
- price has become uncompetitive
- ratings/reviews have dropped
- popular variations have run out (hidden OOS within the card)
One-Click Test: What to Turn Off for 24 Hours to Understand the Cause
If the situation is not critical and you can afford the test:
Test 1: Turn off broad advertising campaigns for 24 hours
- if sales have hardly dropped, and DRR has improved → part of the advertising was junk/cannibalizing organic
- if sales have sharply dropped → advertising was indeed holding demand (or organic is weak)
Test 2: Check the “warehouse version”
Even without turning off advertising: open the card as a buyer and compare:
- delivery time “yesterday” (if you remember) vs “today”
- availability of popular variations
If delivery has worsened — this is almost always an inventory issue.
Mini-Diagnosis Checklist (10 minutes)
- Open the card as a buyer: can it be purchased? what is the delivery?
- Inventory across warehouses and variations (are there popular options?)
- DRR today vs yesterday/7 days
- CR of the card today vs yesterday/7 days
- Top-3 campaigns and top-5 SKUs by expenses — is there a waste without orders?
- Are there promotions/discounts/price changes that could have impacted margin and demand?
Common Mistakes in Diagnosis
- treating OOS with advertising (first inventory, then traffic)
- looking at “total inventory” and ignoring delivery across warehouses
- comparing “today” with “average for the month”
- optimizing bids when the problem is with card conversion
- not separating causes: inventory may be the primary cause, while advertising is an amplifier