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Ecommerce has become one of the most important growth channels for consumer products companies. But for many organizations, channels like Amazon introduce volatility, complexity, and execution pressure that traditional planning processes were not designed to handle.
The challenge is not selling to a new customer, but managing a channel where demand signals change quickly, availability expectations are high, penalties can be costly, and inventory decisions must be made across an increasingly complex network.
When planning fails, the impact is immediate: missed sales, excess inventory, customer fines, expedited freight, poor service levels, and declining stakeholder confidence.
“Ecommerce demand volatility becomes even more challenging during major promotional events. Prime Day, Singles’ Day, Cyber Week, Black Friday, and category-specific promotions can create demand spikes that are many multiples of normal run rates.”
Tony Schlader
Account Executive, Consumer Products
Ecommerce Demand Is Difficult to Forecast
Amazon and other ecommerce channels create demand patterns that are often more volatile than traditional retail. Promotions, search ranking, pricing changes, competitor activity, media spend, customer reviews, and inventory availability can all influence demand in real time.
Yet many companies still forecast ecommerce using the same historical shipment-based methods they use for traditional channels. That creates a disconnect.
Shipment history may show what was supplied, but it does not always show what customers actually wanted. If a product was out of stock, constrained, suppressed in search results, or impacted by a promotion, the historical signal can be misleading. The forecast then carries those distortions forward.
The result is a cycle of overreaction and underreaction. Companies build too much inventory on the wrong items, run short on the right items, and struggle to separate true demand changes from temporary noise.
Inaccurate Forecasts Create Inventory Problems Across the Network
Poor ecommerce forecasting does not remain confined to the demand plan. It quickly becomes an inventory problem. If demand is understated, companies miss sales and risk losing digital shelf position. If demand is overstated, inventory builds in the wrong node, tying up working capital and creating downstream markdown, storage, or obsolescence risk.
The issue becomes more difficult when inventory is spread across plants, distribution centers, Amazon fulfillment locations, third-party logistics providers, and retail channels. Having enough inventory in total is not enough. The inventory must be in the right place, at the right time, in the right quantity.
For many organizations, ecommerce planning breaks down because inventory policies are not optimized across the full network. Teams manage safety stock, replenishment, allocation, and deployment in silos. One location may expedite product while another holds excess. Amazon may face a stockout while another channel is over-inventoried.
This is where ecommerce becomes a network planning challenge, not just a forecasting challenge.
The Cost of Missing Tentpole Events
Ecommerce demand volatility becomes even more challenging during major promotional events. Prime Day, Singles’ Day, Cyber Week, Black Friday, and category-specific promotions can create demand spikes that are many multiples of normal run rates.
For brands selling through Amazon, these events represent both an enormous opportunity and a significant risk. Forecasts developed months earlier must account for promotional lift, marketing investments, competitor actions, inventory constraints, and shifting consumer behavior. Small forecasting errors can have outsized consequences.
When inventory is insufficient, companies risk:
- Lost sales during the highest-demand periods of the year
- Reduced product ranking and visibility
- Missed promotional opportunities
- Increased stockout rates and lower service levels
- Diminished market share that may persist after the event ends
Overestimating demand creates a different challenge. Excess inventory left behind after a tentpole event can increase storage costs, tie up working capital, and force future markdowns or promotional activity.
Unlike a typical week of demand, there is often little opportunity to recover once a tentpole event begins. Inventory must already be in the right location, replenishment plans must already be aligned, and suppliers must already be prepared to respond.
Success during these events depends on an organization's ability to connect forecasting, inventory planning, supply planning, and execution into a single coordinated process.
Optimized Inventory Requires a Connected Planning Model
To serve ecommerce profitably, companies need to move beyond static inventory targets and disconnected replenishment rules.
They need to understand how demand variability, supply constraints, lead times, service targets, margin, and fulfillment costs interact across the network. Inventory decisions should account for where the product is needed, how quickly it can move, the required service level, and the trade-offs among cost, revenue, and customer performance.
The inventory challenge becomes particularly acute ahead of major ecommerce events. Inventory must not only be available across the network but also positioned weeks in advance to support expected demand surges. A stockout during Prime Day can result in more lost revenue than weeks of normal demand, while excess inventory after the event can lead to months of carrying and markdown costs.
In practical terms, this means planning teams need the ability to:
- Sense demand changes
- Identify forecast bias and demand-shaping events
- Optimize inventory by node and channel
- Balance Amazon requirements with broader network priorities
- Simulate service, cost, and revenue trade-offs
- Reallocate inventory before problems become execution issues
Digital tools like Multi-Echelon Inventory Optimization (MEIO) are excellent solutions to deploy these capabilities at scale.
“A true connected planning process and toolset allows companies, customers, and suppliers to operate from a shared view of demand, supply, inventory, and risk. That makes it easier to align on priorities, resolve exceptions, and keep products flowing. ”
Tony Schlader
Account Executive, Consumer Products
Collaboration Is Critical to Seamless Execution
Ecommerce also requires stronger collaboration with both customers and suppliers.
On the customer side, companies need better visibility into promotions, ordering patterns, inventory positions, service expectations, and future demand drivers. With Amazon, this may include vendor forecasts, purchase orders, sell-through signals, chargebacks, availability metrics, and promotional plans.
On the supplier side, companies need clear visibility into capacity, material constraints, lead times, production schedules, and potential risks. When demand shifts quickly, supply teams need to know whether suppliers can respond, where constraints exist, and what alternatives are available.
When this information is managed through spreadsheets, emails, portals, and disconnected systems, response time slows. Teams spend more time reconciling data than making decisions.
A true connected planning process and toolset allows companies, customers, and suppliers to operate from a shared view of demand, supply, inventory, and risk. That makes it easier to align on priorities, resolve exceptions, and keep products flowing.
How o9 Helps Companies Plan for Ecommerce Complexity
o9 helps companies connect demand planning, inventory optimization, supply planning, and collaboration into a single planning foundation.
By bringing together sell-in, POS, customer, supplier, inventory, and network data, companies can move from reactive ecommerce execution to proactive decision-making.
This enables planning teams to:
- Improve forecast accuracy using richer demand signals
- Detect demand shifts, bias, and exceptions earlier
- Optimize inventory across the end-to-end network
- Evaluate trade-offs between service, cost, and working capital
- Collaborate with customers and suppliers in a shared planning environment
- Respond faster when ecommerce demand changes
For many organizations, annual performance is disproportionately influenced by a handful of ecommerce tentpole events. The companies that consistently win are those that can accurately anticipate demand, optimize inventory positioning across their network, and collaborate effectively with both customers and suppliers to ensure excellent execution.
Ecommerce growth creates complexity. But with the right planning model, companies can turn that complexity into a competitive advantage.
About the authors
The Editorial Team, o9
A multidisciplinary collective of editors, strategists, technologists, and former executives with experience across Fortune 500 companies and top consulting firms. Grounded in o9’s mission to help enterprises make faster, better decisions through the power of AI-driven planning and execution software, the team shares clear, practical insights on digital transformation, supply chain, and enterprise planning to support business leaders in navigating complexity and driving change.
