diff --git a/workers/main/src/configs/weeklyFinancialReport.ts b/workers/main/src/configs/weeklyFinancialReport.ts
index e40c0da..0c5ba49 100644
--- a/workers/main/src/configs/weeklyFinancialReport.ts
+++ b/workers/main/src/configs/weeklyFinancialReport.ts
@@ -2,3 +2,6 @@ export enum GroupNameEnum {
   SD_REPORT = 'SD Weekly Financial Report',
   ED_REPORT = 'ED Weekly Financial Report',
 }
+
+export const HIGH_MARGINALITY_THRESHOLD = 55;
+export const MEDIUM_MARGINALITY_THRESHOLD = 45;
diff --git a/workers/main/src/services/WeeklyFinancialReport/GroupAggregator.ts b/workers/main/src/services/WeeklyFinancialReport/GroupAggregator.ts
new file mode 100644
index 0000000..d0b0abc
--- /dev/null
+++ b/workers/main/src/services/WeeklyFinancialReport/GroupAggregator.ts
@@ -0,0 +1,15 @@
+import type { TargetUnit } from '../../common/types';
+
+export class GroupAggregator {
+  static aggregateGroup(targetUnits: TargetUnit[], targetUnitId: number) {
+    const groupUnits = targetUnits.filter(
+      (targetUnit) => targetUnit.group_id === targetUnitId,
+    );
+    const groupTotalHours = groupUnits.reduce(
+      (sum, unit) => sum + unit.total_hours,
+      0,
+    );
+
+    return { groupUnits, groupTotalHours };
+  }
+}
diff --git a/workers/main/src/services/WeeklyFinancialReport/IWeeklyFinancialReportRepository.ts b/workers/main/src/services/WeeklyFinancialReport/IWeeklyFinancialReportRepository.ts
new file mode 100644
index 0000000..c1b329b
--- /dev/null
+++ b/workers/main/src/services/WeeklyFinancialReport/IWeeklyFinancialReportRepository.ts
@@ -0,0 +1,20 @@
+import { TargetUnit } from '../../common/types';
+import { Employee, Project } from '../FinApp';
+
+export interface GenerateReportInput {
+  targetUnits: TargetUnit[];
+  employees: Employee[];
+  projects: Project[];
+}
+
+export interface IWeeklyFinancialReportRepository {
+  generateReport(
+    params: GenerateReportInput,
+  ): Promise<{ summary: string; details: string }>;
+}
+
+export interface AggregateGroupDataInput {
+  groupUnits: TargetUnit[];
+  employees: Employee[];
+  projects: Project[];
+}
diff --git a/workers/main/src/services/WeeklyFinancialReport/MarginalityCalculator.ts b/workers/main/src/services/WeeklyFinancialReport/MarginalityCalculator.ts
new file mode 100644
index 0000000..74c1d68
--- /dev/null
+++ b/workers/main/src/services/WeeklyFinancialReport/MarginalityCalculator.ts
@@ -0,0 +1,47 @@
+import {
+  HIGH_MARGINALITY_THRESHOLD,
+  MEDIUM_MARGINALITY_THRESHOLD,
+} from '../../configs/weeklyFinancialReport';
+
+export enum MarginalityLevel {
+  High = 'high',
+  Medium = 'medium',
+  Low = 'low',
+}
+
+export interface MarginalityResult {
+  marginAmount: number;
+  marginalityPercent: number;
+  indicator: string;
+  level: MarginalityLevel;
+}
+
+export class MarginalityCalculator {
+  static calculate(revenue: number, cogs: number): MarginalityResult {
+    const marginAmount = revenue - cogs;
+    const marginalityPercent = revenue > 0 ? (marginAmount / revenue) * 100 : 0;
+    const level = this.classify(marginalityPercent);
+    const indicator = this.getIndicator(level);
+
+    return { marginAmount, marginalityPercent, indicator, level };
+  }
+
+  static classify(percent: number): MarginalityLevel {
+    if (percent >= HIGH_MARGINALITY_THRESHOLD) return MarginalityLevel.High;
+    if (percent >= MEDIUM_MARGINALITY_THRESHOLD) return MarginalityLevel.Medium;
+
+    return MarginalityLevel.Low;
+  }
+
+  static getIndicator(level: MarginalityLevel): string {
+    switch (level) {
+      case MarginalityLevel.High:
+        return ':arrowup:';
+      case MarginalityLevel.Medium:
+        return ':large_yellow_circle:';
+      case MarginalityLevel.Low:
+      default:
+        return ':arrowdown:';
+    }
+  }
+}
diff --git a/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportFormatter.ts b/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportFormatter.ts
new file mode 100644
index 0000000..debae35
--- /dev/null
+++ b/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportFormatter.ts
@@ -0,0 +1,84 @@
+import { formatCurrency } from '../../common/formatUtils';
+import {
+  HIGH_MARGINALITY_THRESHOLD,
+  MEDIUM_MARGINALITY_THRESHOLD,
+} from '../../configs/weeklyFinancialReport';
+
+export interface formatSummaryInput {
+  reportTitle: string;
+  highGroups: string[];
+  mediumGroups: string[];
+  lowGroups: string[];
+}
+
+export interface FormatDetailInput {
+  groupName: string;
+  groupTotalHours: number;
+  currentQuarter: string;
+  groupTotalRevenue: number;
+  groupTotalCogs: number;
+  marginAmount: number;
+  marginalityPercent: number;
+  indicator: string;
+}
+
+const spacer = ' '.repeat(4);
+
+export class WeeklyFinancialReportFormatter {
+  static formatDetail = ({
+    groupName,
+    groupTotalHours,
+    currentQuarter,
+    groupTotalRevenue,
+    groupTotalCogs,
+    marginAmount,
+    marginalityPercent,
+    indicator,
+  }: FormatDetailInput) =>
+    `${indicator} *${groupName}* (${groupTotalHours}h)\n` +
+    `${spacer}*Period*: ${currentQuarter}\n` +
+    `${spacer}*Revenue*: ${formatCurrency(groupTotalRevenue)}\n` +
+    `${spacer}*COGS*: ${formatCurrency(groupTotalCogs)}\n` +
+    `${spacer}*Margin*: ${formatCurrency(marginAmount)}\n` +
+    `${spacer}*Marginality*: ${marginalityPercent.toFixed(0)}%\n\n`;
+
+  static formatSummary = ({
+    reportTitle,
+    highGroups,
+    mediumGroups,
+    lowGroups,
+  }: formatSummaryInput) => {
+    let summary = `${reportTitle}\n`;
+
+    if (highGroups.length) {
+      summary += '________________________________\n';
+      summary += `:arrowup: *Marginality is ${HIGH_MARGINALITY_THRESHOLD}% or higher*:\n`;
+      summary += `${spacer}${highGroups.join(`\n${spacer}`)}\n`;
+    }
+
+    if (mediumGroups.length) {
+      summary += '__________________________________\n';
+      summary += ` :large_yellow_circle:  *Marginality is between ${MEDIUM_MARGINALITY_THRESHOLD}-${HIGH_MARGINALITY_THRESHOLD}%*:\n`;
+      summary += `${spacer}${mediumGroups.join(`\n${spacer}`)}\n`;
+    }
+
+    if (lowGroups.length) {
+      summary += '__________________________________\n';
+      summary += `:arrowdown: *Marginality is under ${MEDIUM_MARGINALITY_THRESHOLD}%*:\n`;
+      summary += `${spacer}${lowGroups.join(`\n${spacer}`)}\n`;
+    }
+
+    summary += ' -------------------------------------------\n';
+    summary += 'The specific figures will be available in the thread';
+
+    return summary;
+  };
+
+  static formatFooter = (totalHours: number) =>
+    `\n*Total hours*: ${totalHours}h\n\n` +
+    '*Notes:*\n' +
+    '1. *Contract Type* is not implemented\n' +
+    '2. *Effective Revenue* is not implemented\n' +
+    '3. *Dept Tech* hours are not implemented\n\n' +
+    `*Legend*: Marginality :arrowup: ≥${HIGH_MARGINALITY_THRESHOLD}%   :large_yellow_circle: ${MEDIUM_MARGINALITY_THRESHOLD}-${HIGH_MARGINALITY_THRESHOLD - 1}%  :arrowdown: <${MEDIUM_MARGINALITY_THRESHOLD}%`;
+}
diff --git a/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportRepository.test.ts b/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportRepository.test.ts
new file mode 100644
index 0000000..96b090f
--- /dev/null
+++ b/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportRepository.test.ts
@@ -0,0 +1,136 @@
+import { describe, expect, it } from 'vitest';
+
+import { WeeklyFinancialReportRepository } from './WeeklyFinancialReportRepository';
+
+describe('WeeklyFinancialReportRepository', () => {
+  const repo = new WeeklyFinancialReportRepository();
+
+  const targetUnits = [
+    {
+      group_id: 1,
+      group_name: 'Group A',
+      project_id: 10,
+      project_name: 'Project X',
+      user_id: 100,
+      username: 'Alice',
+      spent_on: '2024-06-01',
+      total_hours: 8,
+    },
+    {
+      group_id: 1,
+      group_name: 'Group A',
+      project_id: 10,
+      project_name: 'Project X',
+      user_id: 101,
+      username: 'Bob',
+      spent_on: '2024-06-01',
+      total_hours: 4,
+    },
+    {
+      group_id: 2,
+      group_name: 'Group B',
+      project_id: 20,
+      project_name: 'Project Y',
+      user_id: 102,
+      username: 'Charlie',
+      spent_on: '2024-06-01',
+      total_hours: 5,
+    },
+    {
+      group_id: 3,
+      group_name: 'Group C',
+      project_id: 30,
+      project_name: 'Project Z',
+      user_id: 103,
+      username: 'David',
+      spent_on: '2024-06-01',
+      total_hours: 100,
+    },
+    {
+      group_id: 4,
+      group_name: 'Group D',
+      project_id: 40,
+      project_name: 'Project W',
+      user_id: 104,
+      username: 'Eve',
+      spent_on: '2024-06-01',
+      total_hours: 10,
+    },
+  ];
+  const employees = [
+    { redmine_id: 100, history: { rate: { '2024-01-01': 100 } } },
+    { redmine_id: 101, history: { rate: { '2024-01-01': 200 } } },
+    { redmine_id: 102, history: { rate: { '2024-01-01': 300 } } },
+    { redmine_id: 103, history: { rate: { '2024-01-01': 900 } } },
+    { redmine_id: 104, history: { rate: { '2024-01-01': 700 } } },
+  ];
+  const projects = [
+    { redmine_id: 10, history: { rate: { '2024-01-01': 500 } } },
+    { redmine_id: 20, history: { rate: { '2024-01-01': 1000 } } },
+    { redmine_id: 30, history: { rate: { '2024-01-01': 1500 } } },
+    { redmine_id: 40, history: { rate: { '2024-01-01': 1300 } } },
+  ];
+
+  it('generates a report with summary and details', async () => {
+    const { summary, details } = await repo.generateReport({
+      targetUnits,
+      employees,
+      projects,
+    });
+
+    expect(typeof summary).toBe('string');
+    expect(typeof details).toBe('string');
+    expect(summary.length).toBeGreaterThan(0);
+    expect(details.length).toBeGreaterThan(0);
+
+    // Check summary content
+    expect(summary).toContain('Weekly Financial Summary for Target Units');
+    expect(summary).toContain('Marginality is 55% or higher');
+    expect(summary).toContain('Marginality is between 45-55%');
+    expect(summary).toContain('Marginality is under 45%');
+    expect(summary).toContain(
+      'The specific figures will be available in the thread',
+    );
+    // Group names should appear in summary
+    expect(summary).toContain('Group A');
+    expect(summary).toContain('Group B');
+    expect(summary).toContain('Group C');
+    expect(summary).toContain('Group D');
+
+    // Check details content
+    expect(details).toContain('Total hours');
+    expect(details).toContain('Group A');
+    expect(details).toContain('Group B');
+    expect(details).toContain('Group C');
+    expect(details).toContain('Group D');
+    expect(details).toMatch(/\*Period\*: Q\d/);
+    expect(details).toContain('Revenue');
+    expect(details).toContain('COGS');
+    expect(details).toContain('Margin');
+    expect(details).toContain('Marginality');
+    expect(details).toContain('Notes:');
+    expect(details).toContain('Contract Type');
+    expect(details).toContain('Effective Revenue');
+    expect(details).toContain('Dept Tech');
+    expect(details).toContain('Legend');
+    // Marginality indicators
+    expect(details).toMatch(/:arrow(up|down):|:large_yellow_circle:/);
+    // Check for correct currency formatting
+    expect(details).toMatch(/\$[\d,]+/);
+  });
+
+  it('handles empty input arrays', async () => {
+    const { summary, details } = await repo.generateReport({
+      targetUnits: [],
+      employees: [],
+      projects: [],
+    });
+
+    expect(typeof summary).toBe('string');
+    expect(typeof details).toBe('string');
+    expect(details).toContain('*Total hours*: 0h');
+    expect(details).toContain('Notes:');
+    expect(details).toContain('Legend');
+    expect(summary).toContain('Weekly Financial Summary for Target Units');
+  });
+});
diff --git a/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportRepository.ts b/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportRepository.ts
new file mode 100644
index 0000000..88fdf3f
--- /dev/null
+++ b/workers/main/src/services/WeeklyFinancialReport/WeeklyFinancialReportRepository.ts
@@ -0,0 +1,202 @@
+import { getRateByDate } from '../../common/formatUtils';
+import type { TargetUnit } from '../../common/types';
+import type { Employee, Project } from '../FinApp';
+import { GroupAggregator } from './GroupAggregator';
+import {
+  AggregateGroupDataInput,
+  GenerateReportInput,
+  IWeeklyFinancialReportRepository,
+} from './IWeeklyFinancialReportRepository';
+import {
+  MarginalityCalculator,
+  MarginalityLevel,
+} from './MarginalityCalculator';
+import { WeeklyFinancialReportFormatter } from './WeeklyFinancialReportFormatter';
+
+interface ProcessTargetUnitInput {
+  targetUnit: TargetUnit;
+  targetUnits: TargetUnit[];
+  employees: Employee[];
+  projects: Project[];
+  processedGroupIds: Set<number>;
+  currentQuarter: string;
+  highMarginalityGroups: string[];
+  mediumMarginalityGroups: string[];
+  lowMarginalityGroups: string[];
+  updateReportDetails: (detail: string) => void;
+  updateTotalReportedHours: (hours: number) => void;
+}
+
+export class WeeklyFinancialReportRepository
+  implements IWeeklyFinancialReportRepository
+{
+  async generateReport({
+    targetUnits,
+    employees,
+    projects,
+  }: GenerateReportInput) {
+    const currentDate = new Date();
+    const reportTitle = this.composeWeeklyReportTitle(currentDate);
+    const processedGroupIds = new Set<number>();
+    let reportDetails = '';
+    let totalReportedHours = 0;
+    const currentQuarter = `Q${Math.floor(currentDate.getMonth() / 3) + 1}`;
+    const highGroups: string[] = [];
+    const mediumGroups: string[] = [];
+    const lowGroups: string[] = [];
+
+    for (const targetUnit of targetUnits) {
+      this.processTargetUnit({
+        targetUnit,
+        targetUnits,
+        employees,
+        projects,
+        processedGroupIds,
+        currentQuarter,
+        highMarginalityGroups: highGroups,
+        mediumMarginalityGroups: mediumGroups,
+        lowMarginalityGroups: lowGroups,
+        updateReportDetails: (detail) => (reportDetails += detail),
+        updateTotalReportedHours: (hours) => (totalReportedHours += hours),
+      });
+    }
+
+    reportDetails +=
+      WeeklyFinancialReportFormatter.formatFooter(totalReportedHours);
+
+    const reportSummary = WeeklyFinancialReportFormatter.formatSummary({
+      reportTitle,
+      highGroups,
+      mediumGroups,
+      lowGroups,
+    });
+
+    return {
+      details: reportDetails,
+      summary: reportSummary,
+    };
+  }
+
+  private processTargetUnit({
+    targetUnit,
+    targetUnits,
+    employees,
+    projects,
+    processedGroupIds,
+    currentQuarter,
+    highMarginalityGroups,
+    mediumMarginalityGroups,
+    lowMarginalityGroups,
+    updateReportDetails,
+    updateTotalReportedHours,
+  }: ProcessTargetUnitInput) {
+    if (!processedGroupIds.has(targetUnit.group_id)) {
+      processedGroupIds.add(targetUnit.group_id);
+
+      const { groupUnits, groupTotalHours } = GroupAggregator.aggregateGroup(
+        targetUnits,
+        targetUnit.group_id,
+      );
+      const { groupTotalCogs, groupTotalRevenue } = this.aggregateGroupData({
+        groupUnits,
+        employees,
+        projects,
+      });
+      const marginality = MarginalityCalculator.calculate(
+        groupTotalRevenue,
+        groupTotalCogs,
+      );
+
+      this.pushGroupByMarginality(marginality.level, targetUnit.group_name, {
+        highMarginalityGroups,
+        mediumMarginalityGroups,
+        lowMarginalityGroups,
+      });
+      updateReportDetails(
+        WeeklyFinancialReportFormatter.formatDetail({
+          groupName: targetUnit.group_name,
+          groupTotalHours,
+          currentQuarter,
+          groupTotalRevenue,
+          groupTotalCogs,
+          marginAmount: marginality.marginAmount,
+          marginalityPercent: marginality.marginalityPercent,
+          indicator: marginality.indicator,
+        }),
+      );
+      updateTotalReportedHours(groupTotalHours);
+    }
+  }
+
+  private pushGroupByMarginality(
+    level: MarginalityLevel,
+    groupName: string,
+    groups: {
+      highMarginalityGroups: string[];
+      mediumMarginalityGroups: string[];
+      lowMarginalityGroups: string[];
+    },
+  ) {
+    switch (level) {
+      case MarginalityLevel.High:
+        groups.highMarginalityGroups.push(groupName);
+        break;
+      case MarginalityLevel.Medium:
+        groups.mediumMarginalityGroups.push(groupName);
+        break;
+      case MarginalityLevel.Low:
+        groups.lowMarginalityGroups.push(groupName);
+        break;
+    }
+  }
+
+  private composeWeeklyReportTitle(currentDate: Date): string {
+    const periodStart = new Date(
+      currentDate.getFullYear(),
+      currentDate.getMonth(),
+      currentDate.getDate() - ((currentDate.getDay() + 6) % 7) - 7,
+    )
+      .toISOString()
+      .slice(0, 10);
+    const periodEnd = new Date(
+      currentDate.getFullYear(),
+      currentDate.getMonth(),
+      currentDate.getDate() - ((currentDate.getDay() + 6) % 7) - 1,
+    )
+      .toISOString()
+      .slice(0, 10);
+
+    return `*Weekly Financial Summary for Target Units* (${periodStart} - ${periodEnd})`;
+  }
+
+  private safeGetRate(
+    history: Employee['history'] | undefined,
+    date: string,
+  ): number {
+    if (!history || typeof history !== 'object' || !history.rate) return 0;
+
+    return getRateByDate(history.rate, date) || 0;
+  }
+
+  private aggregateGroupData({
+    groupUnits,
+    employees,
+    projects,
+  }: AggregateGroupDataInput) {
+    let groupTotalCogs = 0;
+    let groupTotalRevenue = 0;
+
+    for (const unit of groupUnits) {
+      const employee = employees.find((e) => e.redmine_id === unit.user_id);
+      const project = projects.find((p) => p.redmine_id === unit.project_id);
+      const date = unit.spent_on;
+      const employeeRate = this.safeGetRate(employee?.history, date);
+      const projectRate = this.safeGetRate(project?.history, date);
+
+      groupTotalCogs += employeeRate * unit.total_hours;
+      groupTotalRevenue += projectRate * unit.total_hours;
+    }
+
+    return { groupTotalCogs, groupTotalRevenue };
+  }
+}
diff --git a/workers/main/src/services/WeeklyFinancialReport/index.ts b/workers/main/src/services/WeeklyFinancialReport/index.ts
new file mode 100644
index 0000000..a13ba15
--- /dev/null
+++ b/workers/main/src/services/WeeklyFinancialReport/index.ts
@@ -0,0 +1 @@
+export * from './WeeklyFinancialReportRepository';