diff --git a/backend/app/models/dividend.rb b/backend/app/models/dividend.rb
index 756a4972f6..6862833bdc 100644
--- a/backend/app/models/dividend.rb
+++ b/backend/app/models/dividend.rb
@@ -29,6 +29,7 @@ class Dividend < ApplicationRecord
   validates :withholding_percentage, numericality: { greater_than_or_equal_to: 0, only_integer: true }, allow_nil: true
   validates :net_amount_in_cents, numericality: { greater_than_or_equal_to: 0, only_integer: true }, allow_nil: true
   validates :qualified_amount_cents, numericality: { greater_than_or_equal_to: 0, only_integer: true }
+  validates :investment_amount_cents, presence: true, numericality: { only_integer: true, greater_than_or_equal_to: 0 }
 
   scope :pending_signup, -> { where(status: PENDING_SIGNUP) }
   scope :paid, -> { where(status: PAID) }
diff --git a/backend/app/services/create_investors_and_dividends.rb b/backend/app/services/create_investors_and_dividends.rb
index 17b570916f..8e99a54ec7 100644
--- a/backend/app/services/create_investors_and_dividends.rb
+++ b/backend/app/services/create_investors_and_dividends.rb
@@ -153,6 +153,7 @@ def create_investments_and_dividends
             status: user.current_sign_in_at.nil? ? Dividend::PENDING_SIGNUP : Dividend::ISSUED,
             total_amount_in_cents: dividend_cents,
             qualified_amount_cents: dividend_cents,
+            investment_amount_cents: company_investor.investment_amount_in_cents,
           )
         end
       rescue => e
diff --git a/backend/app/services/onetime/backfill_dividend_investment_amounts.rb b/backend/app/services/onetime/backfill_dividend_investment_amounts.rb
new file mode 100644
index 0000000000..2034fc2b85
--- /dev/null
+++ b/backend/app/services/onetime/backfill_dividend_investment_amounts.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+class Onetime::BackfillDividendInvestmentAmounts
+  def perform
+    backfill_share_based_dividends
+    backfill_convertible_based_dividends
+    backfill_remaining_dividends
+  end
+
+  private
+    # For share-based dividends (number_of_shares IS NOT NULL),
+    # use the company_investor's investment_amount_in_cents
+    def backfill_share_based_dividends
+      Dividend.where(investment_amount_cents: nil)
+              .where.not(number_of_shares: nil)
+              .find_each do |dividend|
+        dividend.update_columns(
+          investment_amount_cents: dividend.company_investor.investment_amount_in_cents
+        )
+      end
+    end
+
+    # For convertible/SAFE-based dividends (number_of_shares IS NULL),
+    # use the sum of convertible_securities.principal_value_in_cents for that investor
+    def backfill_convertible_based_dividends
+      Dividend.where(investment_amount_cents: nil, number_of_shares: nil)
+              .find_each do |dividend|
+        principal = dividend.company_investor
+                            .convertible_securities
+                            .sum(:principal_value_in_cents)
+        dividend.update_columns(investment_amount_cents: principal)
+      end
+    end
+
+    # Fallback: set any remaining NULL values to 0
+    def backfill_remaining_dividends
+      Dividend.where(investment_amount_cents: nil)
+              .update_all(investment_amount_cents: 0)
+    end
+end
diff --git a/backend/config/data/seed_templates/gumroad.json b/backend/config/data/seed_templates/gumroad.json
index fbdb50990d..e5dd0d7edf 100644
--- a/backend/config/data/seed_templates/gumroad.json
+++ b/backend/config/data/seed_templates/gumroad.json
@@ -243,6 +243,7 @@
             "withheld_tax_cents": 0,
             "qualified_amount_cents": 0,
             "number_of_shares": 1230,
+            "investment_amount_cents": 317340,
             "status": "Paid"
           },
           "convertible_securities": [
diff --git a/backend/db/migrate/20260209000001_make_dividends_investment_amount_cents_not_null.rb b/backend/db/migrate/20260209000001_make_dividends_investment_amount_cents_not_null.rb
new file mode 100644
index 0000000000..ce4c4f04c1
--- /dev/null
+++ b/backend/db/migrate/20260209000001_make_dividends_investment_amount_cents_not_null.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class MakeDividendsInvestmentAmountCentsNotNull < ActiveRecord::Migration[7.0]
+  def up
+    # Ensure no NULL values remain before adding the constraint.
+    # The Onetime::BackfillDividendInvestmentAmounts script should be run first,
+    # but this acts as a safety net.
+    Dividend.where(investment_amount_cents: nil).update_all(investment_amount_cents: 0)
+
+    change_column_null :dividends, :investment_amount_cents, false
+  end
+
+  def down
+    change_column_null :dividends, :investment_amount_cents, true
+  end
+end
diff --git a/backend/db/schema.rb b/backend/db/schema.rb
index ebdc0f3193..de9b321246 100644
--- a/backend/db/schema.rb
+++ b/backend/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2026_01_28_070657) do
+ActiveRecord::Schema[8.0].define(version: 2026_02_09_000001) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "citext"
   enable_extension "pg_catalog.plpgsql"
@@ -377,7 +377,7 @@
     t.bigint "user_compliance_info_id"
     t.bigint "qualified_amount_cents", null: false
     t.datetime "signed_release_at"
-    t.bigint "investment_amount_cents"
+    t.bigint "investment_amount_cents", null: false
     t.string "external_id", null: false
     t.index ["company_id"], name: "index_dividends_on_company_id"
     t.index ["company_investor_id"], name: "index_dividends_on_company_investor_id"
diff --git a/backend/spec/services/onetime/backfill_dividend_investment_amounts_spec.rb b/backend/spec/services/onetime/backfill_dividend_investment_amounts_spec.rb
new file mode 100644
index 0000000000..8e10db16ff
--- /dev/null
+++ b/backend/spec/services/onetime/backfill_dividend_investment_amounts_spec.rb
@@ -0,0 +1,124 @@
+# frozen_string_literal: true
+
+RSpec.describe Onetime::BackfillDividendInvestmentAmounts do
+  describe "#perform" do
+    subject(:service) { described_class.new }
+
+    let(:company) { create(:company) }
+    let(:dividend_round) { create(:dividend_round, company:) }
+
+    # The column is NOT NULL in schema.rb (post-migration state), but the backfill
+    # script runs before the migration. Temporarily drop the constraint to simulate.
+    before do
+      ActiveRecord::Base.connection.execute(
+        "ALTER TABLE dividends ALTER COLUMN investment_amount_cents DROP NOT NULL"
+      )
+    end
+
+    after do
+      ActiveRecord::Base.connection.execute(
+        "UPDATE dividends SET investment_amount_cents = 0 WHERE investment_amount_cents IS NULL"
+      )
+      ActiveRecord::Base.connection.execute(
+        "ALTER TABLE dividends ALTER COLUMN investment_amount_cents SET NOT NULL"
+      )
+    end
+
+    context "when dividends are share-based" do
+      let(:company_investor) { create(:company_investor, company:, investment_amount_in_cents: 500_00) }
+
+      let!(:dividend) do
+        create(:dividend, company:, company_investor:, dividend_round:, number_of_shares: 100).tap do |d|
+          d.update_columns(investment_amount_cents: nil)
+        end
+      end
+
+      it "backfills from company_investor.investment_amount_in_cents" do
+        service.perform
+        expect(dividend.reload.investment_amount_cents).to eq(500_00)
+      end
+    end
+
+    context "when dividends are convertible/SAFE-based" do
+      let(:company_investor) { create(:company_investor, company:, investment_amount_in_cents: 0) }
+      let(:convertible_investment) { create(:convertible_investment, company:) }
+
+      let!(:convertible_security) do
+        create(:convertible_security,
+               company_investor:,
+               convertible_investment:,
+               principal_value_in_cents: 250_000_00)
+      end
+
+      let!(:dividend) do
+        create(:dividend, company:, company_investor:, dividend_round:, number_of_shares: nil, total_amount_in_cents: 5000, investment_amount_cents: 0).tap do |d|
+          d.update_columns(investment_amount_cents: nil)
+        end
+      end
+
+      it "backfills from convertible_securities.principal_value_in_cents" do
+        service.perform
+        expect(dividend.reload.investment_amount_cents).to eq(250_000_00)
+      end
+    end
+
+    context "when dividends already have investment_amount_cents" do
+      let(:company_investor) { create(:company_investor, company:, investment_amount_in_cents: 100_00) }
+
+      let!(:dividend) do
+        create(:dividend, company:, company_investor:, dividend_round:, investment_amount_cents: 999_99)
+      end
+
+      it "does not overwrite existing values" do
+        service.perform
+        expect(dividend.reload.investment_amount_cents).to eq(999_99)
+      end
+    end
+
+    context "when a company_investor has no shares or securities" do
+      let(:company_investor) { create(:company_investor, company:, investment_amount_in_cents: 0) }
+
+      let!(:dividend) do
+        create(:dividend, company:, company_investor:, dividend_round:, number_of_shares: nil, total_amount_in_cents: 1000, investment_amount_cents: 0).tap do |d|
+          d.update_columns(investment_amount_cents: nil)
+        end
+      end
+
+      it "falls back to 0" do
+        service.perform
+        expect(dividend.reload.investment_amount_cents).to eq(0)
+      end
+    end
+
+    context "with multiple dividends across different investors" do
+      let(:share_investor) { create(:company_investor, company:, investment_amount_in_cents: 300_00) }
+      let(:safe_investor) { create(:company_investor, company:, investment_amount_in_cents: 0) }
+      let(:convertible_investment) { create(:convertible_investment, company:) }
+
+      let!(:convertible_security) do
+        create(:convertible_security,
+               company_investor: safe_investor,
+               convertible_investment:,
+               principal_value_in_cents: 100_000_00)
+      end
+
+      let!(:share_dividend) do
+        create(:dividend, company:, company_investor: share_investor, dividend_round:, number_of_shares: 50).tap do |d|
+          d.update_columns(investment_amount_cents: nil)
+        end
+      end
+
+      let!(:safe_dividend) do
+        create(:dividend, company:, company_investor: safe_investor, dividend_round:, number_of_shares: nil, total_amount_in_cents: 5000, investment_amount_cents: 0).tap do |d|
+          d.update_columns(investment_amount_cents: nil)
+        end
+      end
+
+      it "backfills both correctly" do
+        service.perform
+        expect(share_dividend.reload.investment_amount_cents).to eq(300_00)
+        expect(safe_dividend.reload.investment_amount_cents).to eq(100_000_00)
+      end
+    end
+  end
+end
diff --git a/frontend/app/(dashboard)/equity/dividend_rounds/[type]/[id]/page.tsx b/frontend/app/(dashboard)/equity/dividend_rounds/[type]/[id]/page.tsx
index 8d9635e60b..deae14771a 100644
--- a/frontend/app/(dashboard)/equity/dividend_rounds/[type]/[id]/page.tsx
+++ b/frontend/app/(dashboard)/equity/dividend_rounds/[type]/[id]/page.tsx
@@ -42,9 +42,6 @@ const DividendRound = ({ id }: { id: string }) => {
     dividendRoundId: id,
   });
 
-  // Old dividend records don't have an investment amount
-  const hasInvestmentAmounts = dividends.some((dividend) => dividend.investmentAmountCents !== null);
-
   const columnHelper = createColumnHelper<Dividend>();
   const columns = useMemo(
     () => [
@@ -54,18 +51,14 @@ const DividendRound = ({ id }: { id: string }) => {
         cell: (info) => <div className="font-light">{info.getValue() || "Unknown"}</div>,
         footer: "Total",
       }),
-      ...(hasInvestmentAmounts
-        ? [
-            columnHelper.accessor("investmentAmountCents", {
-              header: "Investment amount",
-              cell: (info) => formatMoneyFromCents(Number(info.getValue())),
-              meta: { numeric: true },
-              footer: formatMoneyFromCents(
-                dividends.reduce((sum, dividend) => sum + Number(dividend.investmentAmountCents), 0),
-              ),
-            }),
-          ]
-        : []),
+      columnHelper.accessor("investmentAmountCents", {
+        header: "Investment amount",
+        cell: (info) => formatMoneyFromCents(Number(info.getValue())),
+        meta: { numeric: true },
+        footer: formatMoneyFromCents(
+          dividends.reduce((sum, dividend) => sum + Number(dividend.investmentAmountCents), 0),
+        ),
+      }),
       columnHelper.accessor("totalAmountInCents", {
         header: "Return amount",
         cell: (info) => formatMoney(Number(info.getValue()) / 100),
diff --git a/frontend/app/(dashboard)/equity/dividends/page.tsx b/frontend/app/(dashboard)/equity/dividends/page.tsx
index 4457da7f31..4b907a2e9b 100644
--- a/frontend/app/(dashboard)/equity/dividends/page.tsx
+++ b/frontend/app/(dashboard)/equity/dividends/page.tsx
@@ -134,7 +134,7 @@ export default function Dividends() {
       columnHelper.simple(
         "investmentAmountCents",
         "Investment amount",
-        (value) => (value ? formatMoneyFromCents(value) : "N/A"),
+        (value) => formatMoneyFromCents(value),
         "numeric",
       ),
       columnHelper.simple("totalAmountInCents", "Gross amount", (value) => formatMoneyFromCents(value), "numeric"),
diff --git a/frontend/db/schema.ts b/frontend/db/schema.ts
index 4e7a2f10dc..15aecd2d65 100644
--- a/frontend/db/schema.ts
+++ b/frontend/db/schema.ts
@@ -447,7 +447,7 @@ export const dividends = pgTable(
     userComplianceInfoId: bigint("user_compliance_info_id", { mode: "bigint" }),
     qualifiedAmountCents: bigint("qualified_amount_cents", { mode: "bigint" }).notNull(),
     signedReleaseAt: timestamp("signed_release_at", { precision: 6, mode: "date" }),
-    investmentAmountCents: bigint("investment_amount_cents", { mode: "bigint" }),
+    investmentAmountCents: bigint("investment_amount_cents", { mode: "bigint" }).notNull(),
     externalId: varchar("external_id").$default(nanoid).notNull(),
   },
   (table) => [